block: move rq_qos_exit() into disk_release()

Keep all teardown of file system I/O related functionality in one place.
There can't be file system I/O in disk_release(), so it is safe to move
rq_qos_exit() there.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220308055200.735835-15-hch@lst.de


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