rust: hrtimer: Add HrTimerInstant

Since we want to add HrTimer methods that can accept Instants, we will want
to make sure that for each method we are using the correct Clocksource for
the given HrTimer. This would get a bit overly-verbose, so add a simple
HrTimerInstant type-alias to handle this for us.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Link: https://lore.kernel.org/r/20250821193259.964504-3-lyude@redhat.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Author: Lyude

rust/kernel/time/hrtimer.rs

@@ -72,6 +72,11 @@ use crate::{prelude::*, types::Opaque};
 use core::marker::PhantomData;
 use pin_init::PinInit;
 
+/// A type-alias to refer to the [`Instant<C>`] for a given `T` from [`HrTimer<T>`].
+///
+/// Where `C` is the [`ClockSource`] of the [`HrTimer`].
+pub type HrTimerInstant<T> = Instant<<<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Clock>;
+
 /// A timer backed by a C `struct hrtimer`.
 ///
 /// # Invariants