Remove trivial to remove uses of atomic-polyfill.

embassy-stm32/src/ipcc.rs

@@ -1,8 +1,7 @@
 use core::future::poll_fn;
+use core::sync::atomic::{compiler_fence, Ordering};
 use core::task::Poll;
 
-use atomic_polyfill::{compiler_fence, Ordering};
-
 use self::sealed::Instance;
 use crate::interrupt;
 use crate::interrupt::typelevel::Interrupt;