ide: don't acquire queue_lock in ide_complete_pm_rq

blk_mq_stop_hw_queues doesn't need any locking, and the ide
dev_flags field isn't protected by it either.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>