Replace futures::future::poll_fn -> core::future::poll_fn.

embassy-nrf/src/saadc.rs

@@ -1,12 +1,12 @@
 #![macro_use]
 
+use core::future::poll_fn;
 use core::sync::atomic::{compiler_fence, Ordering};
 use core::task::Poll;
 
 use embassy_hal_common::drop::OnDrop;
 use embassy_hal_common::{impl_peripheral, into_ref, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
-use futures::future::poll_fn;
 use pac::{saadc, SAADC};
 use saadc::ch::config::{GAIN_A, REFSEL_A, RESP_A, TACQ_A};
 // We treat the positive and negative channels with the same enum values to keep our type tidy and given they are the same