rust: lock: introduce SpinLock

This is the `spinlock_t` lock backend and allows Rust code to use the
kernel spinlock idiomatically.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230419174426.132207-1-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/kernel/sync/lock.rs

@@ -11,6 +11,7 @@ use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned};
 use macros::pin_data;
 
 pub mod mutex;
+pub mod spinlock;
 
 /// The "backend" of a lock.
 ///