- optimize event to parse opcode only once

- optimze channels
- return mut ref for smoltcp rx

embassy-stm32-wpan/src/sub/mac.rs

@@ -94,7 +94,7 @@ impl Mac {
         }
     }
 
-    pub async fn read(&self) -> Event {
+    pub async fn read(&self) -> Result<Event<'_>, ()> {
         Event::new(self.tl_read().await)
     }
 }