Fix clippy errors

libk/src/drivers/io/keyboard.rs

@@ -17,7 +17,7 @@ static WAKER: AtomicWaker = AtomicWaker::new();
 
 pub fn add_scancode(scancode: u8) {
     if let Some(queue) = KBD_QUEUE.get() {
-        if let Err(_) = queue.push(scancode) {
+        if queue.push(scancode).is_err() {
             println!("WARNING: scancode queue full; dropping keyboard input");
         } else {
             WAKER.wake();
@@ -34,7 +34,13 @@ pub struct ScancodeStream {
 impl ScancodeStream {
     pub fn new() -> Self {
         KBD_QUEUE.call_once(|| ArrayQueue::new(5));
-        ScancodeStream { _private: () }
+        Self { _private: () }
+    }
+}
+
+impl Default for ScancodeStream {
+    fn default() -> Self {
+        Self::new()
     }
 }
 
@@ -48,15 +54,12 @@ impl Stream for ScancodeStream {
             return Poll::Ready(Some(scancode));
         }
 
-        WAKER.register(&cx.waker());
+        WAKER.register(cx.waker());
 
-        match queue.pop() {
-            Some(scancode) => {
-                WAKER.take();
-                Poll::Ready(Some(scancode))
-            }
-            None => Poll::Pending,
-        }
+        queue.pop().map_or(Poll::Pending, |scancode| {
+            WAKER.take();
+            Poll::Ready(Some(scancode))
+        })
     }
 }