block: Use the queue_flag_*() functions instead of open-coding these

Except for changing the atomic queue flag manipulations that are
protected by the queue lock into non-atomic manipulations, this
patch does not change any functionality.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7533684..e70cc7d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2678,7 +2678,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
 
 	if (!(set->flags & BLK_MQ_F_SG_MERGE))
-		q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
+		queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);
 
 	q->sg_reserved_size = INT_MAX;