Fix new version Clippy lints

src/adc.rs

@@ -332,16 +332,11 @@ pub struct Active<DmaChan, Buf> {
 /// A collection of channels
 ///
 /// Used to set up multi-channel conversions.
+#[derive(Default)]
 pub struct Channels {
     flags: u32,
 }
 
-impl Default for Channels {
-    fn default() -> Self {
-        Channels { flags: 0 }
-    }
-}
-
 impl Channels {
     pub fn new() -> Channels {
         Default::default()

src/dma.rs

@@ -660,19 +660,9 @@ impl SupportedWordSize for u32 {
     }
 }
 
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Default)]
 pub struct Interrupts {
     pub transfer_error: bool,
     pub half_transfer: bool,
     pub transfer_complete: bool,
 }
-
-impl Default for Interrupts {
-    fn default() -> Self {
-        Self {
-            transfer_error: false,
-            half_transfer: false,
-            transfer_complete: false,
-        }
-    }
-}

src/rtc.rs

@@ -370,24 +370,14 @@ impl Rtc {
 }
 
 /// Flags to enable/disable RTC interrupts.
+#[derive(Default)]
 pub struct Interrupts {
     pub timestamp: bool,
     pub wakeup_timer: bool,
     pub alarm_a: bool,
     pub alarm_b: bool,
 }
 
-impl Default for Interrupts {
-    fn default() -> Self {
-        Self {
-            timestamp: false,
-            wakeup_timer: false,
-            alarm_a: false,
-            alarm_b: false,
-        }
-    }
-}
-
 /// The RTC wakeup timer
 ///
 /// This timer can be used in two ways: