stm32: Remove OptionalPin

The idea behind OptionalPin has a few problems:

- you need to impl the signal traits for NoPin which is a bit weird https://github.com/embassy-rs/embassy/blob/master/embassy-stm32/src/dcmi.rs#L413-L416
- you can pass any combination of set/unset pins, which needs checking at runtime  https://github.com/embassy-rs/embassy/blob/master/embassy-stm32/src/dcmi.rs#L130

The replacement is to do multiple `new` constructors for each combination of pins you want to take.

embassy-stm32/src/pwm/pins.rs

@@ -1,4 +1,4 @@
-use crate::gpio::OptionalPin;
+use crate::gpio::Pin;
 
 #[cfg(feature = "unstable-pac")]
 pub mod low_level {
@@ -6,118 +6,106 @@ pub mod low_level {
 }
 
 pub(crate) mod sealed {
-    use crate::gpio::sealed::OptionalPin;
+    use crate::gpio::sealed::Pin;
 
-    pub trait Channel1Pin<Timer>: OptionalPin {
+    pub trait Channel1Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait Channel1ComplementaryPin<Timer>: OptionalPin {
+    pub trait Channel1ComplementaryPin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
 
-    pub trait Channel2Pin<Timer>: OptionalPin {
+    pub trait Channel2Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait Channel2ComplementaryPin<Timer>: OptionalPin {
+    pub trait Channel2ComplementaryPin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
 
-    pub trait Channel3Pin<Timer>: OptionalPin {
+    pub trait Channel3Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait Channel3ComplementaryPin<Timer>: OptionalPin {
+    pub trait Channel3ComplementaryPin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
 
-    pub trait Channel4Pin<Timer>: OptionalPin {
+    pub trait Channel4Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait Channel4ComplementaryPin<Timer>: OptionalPin {
+    pub trait Channel4ComplementaryPin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
 
-    pub trait ExternalTriggerPin<Timer>: OptionalPin {
+    pub trait ExternalTriggerPin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
 
-    pub trait BreakInputPin<Timer>: OptionalPin {
+    pub trait BreakInputPin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait BreakInputComparator1Pin<Timer>: OptionalPin {
+    pub trait BreakInputComparator1Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait BreakInputComparator2Pin<Timer>: OptionalPin {
+    pub trait BreakInputComparator2Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
 
-    pub trait BreakInput2Pin<Timer>: OptionalPin {
+    pub trait BreakInput2Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait BreakInput2Comparator1Pin<Timer>: OptionalPin {
+    pub trait BreakInput2Comparator1Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
-    pub trait BreakInput2Comparator2Pin<Timer>: OptionalPin {
+    pub trait BreakInput2Comparator2Pin<Timer>: Pin {
         unsafe fn configure(&mut self);
     }
 }
-pub trait Channel1Pin<Timer>: sealed::Channel1Pin<Timer> + OptionalPin + 'static {}
+pub trait Channel1Pin<Timer>: sealed::Channel1Pin<Timer> + Pin + 'static {}
 pub trait Channel1ComplementaryPin<Timer>:
-    sealed::Channel1ComplementaryPin<Timer> + OptionalPin + 'static
+    sealed::Channel1ComplementaryPin<Timer> + Pin + 'static
 {
 }
 
 pub trait Channel2Pin<Timer>: sealed::Channel2Pin<Timer> + 'static {}
 pub trait Channel2ComplementaryPin<Timer>:
-    sealed::Channel2ComplementaryPin<Timer> + OptionalPin + 'static
+    sealed::Channel2ComplementaryPin<Timer> + Pin + 'static
 {
 }
 
 pub trait Channel3Pin<Timer>: sealed::Channel3Pin<Timer> + 'static {}
 pub trait Channel3ComplementaryPin<Timer>:
-    sealed::Channel3ComplementaryPin<Timer> + OptionalPin + 'static
+    sealed::Channel3ComplementaryPin<Timer> + Pin + 'static
 {
 }
 
 pub trait Channel4Pin<Timer>: sealed::Channel4Pin<Timer> + 'static {}
 pub trait Channel4ComplementaryPin<Timer>:
-    sealed::Channel4ComplementaryPin<Timer> + OptionalPin + 'static
+    sealed::Channel4ComplementaryPin<Timer> + Pin + 'static
 {
 }
 
-pub trait ExternalTriggerPin<Timer>:
-    sealed::ExternalTriggerPin<Timer> + OptionalPin + 'static
-{
-}
+pub trait ExternalTriggerPin<Timer>: sealed::ExternalTriggerPin<Timer> + Pin + 'static {}
 
-pub trait BreakInputPin<Timer>: sealed::BreakInputPin<Timer> + OptionalPin + 'static {}
+pub trait BreakInputPin<Timer>: sealed::BreakInputPin<Timer> + Pin + 'static {}
 pub trait BreakInputComparator1Pin<Timer>:
-    sealed::BreakInputComparator1Pin<Timer> + OptionalPin + 'static
+    sealed::BreakInputComparator1Pin<Timer> + Pin + 'static
 {
 }
 pub trait BreakInputComparator2Pin<Timer>:
-    sealed::BreakInputComparator2Pin<Timer> + OptionalPin + 'static
+    sealed::BreakInputComparator2Pin<Timer> + Pin + 'static
 {
 }
 
-pub trait BreakInput2Pin<Timer>: sealed::BreakInput2Pin<Timer> + OptionalPin + 'static {}
+pub trait BreakInput2Pin<Timer>: sealed::BreakInput2Pin<Timer> + Pin + 'static {}
 pub trait BreakInput2Comparator1Pin<Timer>:
-    sealed::BreakInput2Comparator1Pin<Timer> + OptionalPin + 'static
+    sealed::BreakInput2Comparator1Pin<Timer> + Pin + 'static
 {
 }
 pub trait BreakInput2Comparator2Pin<Timer>:
-    sealed::BreakInput2Comparator2Pin<Timer> + OptionalPin + 'static
+    sealed::BreakInput2Comparator2Pin<Timer> + Pin + 'static
 {
 }
 
-macro_rules! impl_no_pin {
-    ($timer:ident, $signal:ident) => {
-        impl crate::pwm::pins::sealed::$signal<crate::peripherals::$timer> for crate::gpio::NoPin {
-            unsafe fn configure(&mut self) {}
-        }
-        impl crate::pwm::pins::$signal<crate::peripherals::$timer> for crate::gpio::NoPin {}
-    };
-}
-
 #[allow(unused)]
 macro_rules! impl_pin {
     ($timer:ident, $signal:ident, $pin:ident, $af:expr) => {