rbd: unfreeze queue after marking disk as dead

Unfreeze queue after returning from blk_mark_disk_dead(), this way at
least allows us to verify queue freeze correctly with lockdep.

Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241031133723.303835-3-ming.lei@redhat.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>