tests: Fix MIRI test errors

Signed-off-by: John Nunley <[email protected]>

Author: notgull

src/no_std.rs

@@ -1267,14 +1267,8 @@ mod tests {
             listeners.listeners[1],
             Entry::Empty(NonZeroUsize::new(4).unwrap())
         );
-        assert_eq!(
-            listeners.listeners[2],
-            Entry::Listener {
-                state: Cell::new(State::Task(Task::Waker(waker))),
-                prev: Cell::new(None),
-                next: Cell::new(Some(key3)),
-            }
-        );
+        assert_eq!(*listeners.listeners[2].prev(), Cell::new(None));
+        assert_eq!(*listeners.listeners[2].next(), Cell::new(Some(key3)));
         assert_eq!(
             listeners.listeners[3],
             Entry::Listener {