block: do more work in elevator_exit

Move the calls to ioc_clear_queue and blk_mq_sched_free_rqs into
elevator_exit.  Except for one call where we know we can't have io_cq
structures yet these always go together, and that extra call in an
error path is harmless.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220308055200.735835-14-hch@lst.de


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