Revert unrelated changes to example to ease review

rp2040-hal/examples/adc_fifo_dma.rs

@@ -27,10 +27,6 @@ use rp2040_hal::Clock;
 // UART related types
 use hal::uart::{DataBits, StopBits, UartConfig};
 
-// ADC related types
-use hal::adc::AdcPin;
-use hal::Adc;
-
 // A shorter alias for the Peripheral Access Crate, which provides low-level
 // register access
 use hal::pac;
@@ -111,13 +107,13 @@ fn main() -> ! {
     let dma = pac.DMA.split(&mut pac.RESETS);
 
     // Enable ADC
-    let mut adc = Adc::new(pac.ADC, &mut pac.RESETS);
+    let mut adc = hal::Adc::new(pac.ADC, &mut pac.RESETS);
 
     // Enable the temperature sense channel
     let mut temperature_sensor = adc.take_temp_sensor().unwrap();
 
     // Configure GPIO26 as an ADC input
-    let adc_pin_0 = AdcPin::new(pins.gpio26.into_floating_input()).unwrap();
+    let adc_pin_0 = hal::adc::AdcPin::new(pins.gpio26.into_floating_input()).unwrap();
 
     // we'll capture 1000 samples in total (500 per channel)
     // NOTE: when calling `shift_8bit` below, the type here must be changed from `u16` to `u8`