stm32: i2c: Clean up conditional code a bit

By moving conditional code inside the functions, we can
reduce duplication and in one case we can even eliminate one...

embassy-stm32/src/i2c/mod.rs

@@ -148,31 +148,20 @@ struct Timeout {
 
 #[allow(dead_code)]
 impl Timeout {
-    #[cfg(not(feature = "time"))]
     #[inline]
     fn check(self) -> Result<(), Error> {
-        Ok(())
-    }
-
         #[cfg(feature = "time")]
-    #[inline]
-    fn check(self) -> Result<(), Error> {
         if Instant::now() > self.deadline {
-            Err(Error::Timeout)
-        } else {
+            return Err(Error::Timeout);
+        }
+
         Ok(())
     }
-    }
 
-    #[cfg(not(feature = "time"))]
     #[inline]
     fn with<R>(self, fut: impl Future<Output = Result<R, Error>>) -> impl Future<Output = Result<R, Error>> {
-        fut
-    }
-
         #[cfg(feature = "time")]
-    #[inline]
-    fn with<R>(self, fut: impl Future<Output = Result<R, Error>>) -> impl Future<Output = Result<R, Error>> {
+        {
             use futures::FutureExt;
 
             embassy_futures::select::select(embassy_time::Timer::at(self.deadline), fut).map(|r| match r {
@@ -180,6 +169,10 @@ impl Timeout {
                 embassy_futures::select::Either::Second(r) => r,
             })
         }
+
+        #[cfg(not(feature = "time"))]
+        fut
+    }
 }
 
 pub(crate) mod sealed {