filelock: add new locks_wake_up_waiter() helper

Currently the function that does this takes a struct file_lock, but
__locks_wake_up_blocks() deals with both locks and leases. Currently
this works because both file_lock and file_lease have the file_lock_core
at the beginning of the struct, but it's fragile to rely on that.

Add a new locks_wake_up_waiter() function and call that from
__locks_wake_up_blocks().

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/20250602-filelock-6-16-v1-1-7da5b2c930fd@kernel.org


Signed-off-by: Christian Brauner <brauner@kernel.org>