bsp(metro_m4)!: Fixes some compiler errors and warnings in examples.

* Fixes a minor compiler warning in the `adc` example.
* Fixes a minor compiler warning in the `async_adc` example.

Author: kyp44

boards/metro_m4/examples/adc.rs

@@ -17,7 +17,7 @@ use bsp::Pins;
 use pac::{CorePeripherals, Peripherals};
 
 use hal::{
-    adc::{Accumulation, Adc, Prescaler, Resolution},
+    adc::{Accumulation, Prescaler},
     clock::v2::{clock_system_at_reset, pclk::Pclk},
 };
 

boards/metro_m4/examples/async_adc.rs

@@ -16,7 +16,7 @@ use bsp::Pins;
 use pac::{CorePeripherals, Peripherals};
 
 use hal::{
-    adc::{Accumulation, Adc, Adc0, Prescaler, Resolution},
+    adc::{Accumulation, Adc0, Prescaler},
     clock::v2::{clock_system_at_reset, pclk::Pclk},
 };