rust: add revocable objects

Imported from revokable.rs form
968b3f1

(Removed test code and fixed a few warnings.)

Signed-off-by: Danilo Krummrich <[email protected]>

Author: metaspace

rust/kernel/lib.rs

@@ -44,6 +44,7 @@ pub mod kunit;
 pub mod net;
 pub mod prelude;
 pub mod print;
+pub mod revocable;
 mod static_assert;
 #[doc(hidden)]
 pub mod std_vendor;