locking: MAINTAINERS: Start watching Rust locking primitives

It makes sense to add Rust locking primitives under the watch of general
locking primitives maintainers. This will encourage more reviews and
find potential issues earlier. Hence add related Rust files into the
LOCKING PRIMITIVES entry in MAINTAINERS.

While we are at it, change the role of myself into the maintainer of
LOCKDEP and RUST to reflect my responsibility for the corresponding
code.

Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
https://lore.kernel.org/lkml/20241128054022.19586-2-boqun.feng@gmail.com/