block: Fix a comment in blk_cleanup_queue()

Change a reference to the legacy block layer into a reference to blk-mq.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: James Smart <james.smart@broadcom.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-core.c

@@ -344,7 +344,8 @@ void blk_cleanup_queue(struct request_queue *q)
 
 	/*
 	 * Drain all requests queued before DYING marking. Set DEAD flag to
-	 * prevent that q->request_fn() gets invoked after draining finished.
+	 * prevent that blk_mq_run_hw_queues() accesses the hardware queues
+	 * after draining finished.
 	 */
 	blk_freeze_queue(q);