rust: devres: provide an accessor for the device

Provide an accessor for the Device a Devres instance has been created
with.

For instance, this is useful when registrations want to provide a
&Device<Bound> for a scope that is protected by Devres.

Suggested-by: Benno Lossin <lossin@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Link: https://lore.kernel.org/r/20250713182737.64448-1-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

rust/kernel/devres.rs

@@ -204,6 +204,11 @@ fn remove_action(&self) -> bool {
         } == 0)
     }
 
+    /// Return a reference of the [`Device`] this [`Devres`] instance has been created with.
+    pub fn device(&self) -> &Device {
+        &self.dev
+    }
+
     /// Obtain `&'a T`, bypassing the [`Revocable`].
     ///
     /// This method allows to directly obtain a `&'a T`, bypassing the [`Revocable`], by presenting