blk-mq: make mq_ops a const pointer

We never change it, make that clear.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 4a2ab5d9..afc81d7 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -60,7 +60,7 @@
 
 struct blk_mq_tag_set {
 	unsigned int		*mq_map;
-	struct blk_mq_ops	*ops;
+	const struct blk_mq_ops	*ops;
 	unsigned int		nr_hw_queues;
 	unsigned int		queue_depth;	/* max hw supported */
 	unsigned int		reserved_tags;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b20da8d..2e99d65 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -407,7 +407,7 @@
 	dma_drain_needed_fn	*dma_drain_needed;
 	lld_busy_fn		*lld_busy_fn;
 
-	struct blk_mq_ops	*mq_ops;
+	const struct blk_mq_ops	*mq_ops;
 
 	unsigned int		*mq_map;