stm32/gpio: expose all functionality as inherent methods.

examples/stm32f3/src/bin/button.rs

@@ -6,7 +6,6 @@
 mod example_common;
 use cortex_m_rt::entry;
 use embassy_stm32::gpio::{Input, Level, Output, Pull, Speed};
-use embedded_hal::digital::v2::{InputPin, OutputPin};
 use example_common::*;
 
 #[entry]
@@ -20,14 +19,14 @@ fn main() -> ! {
     let mut led2 = Output::new(p.PE15, Level::High, Speed::Low);
 
     loop {
-        if unwrap!(button.is_high()) {
+        if button.is_high() {
             info!("high");
-            unwrap!(led1.set_high());
-            unwrap!(led2.set_low());
+            led1.set_high();
+            led2.set_low();
         } else {
             info!("low");
-            unwrap!(led1.set_low());
-            unwrap!(led2.set_high());
+            led1.set_low();
+            led2.set_high();
         }
     }
 }