block: simplify blk_mq_plug

Drop the unused q argument, and invert the check to move the exception
into a branch and the regular path as the normal return.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20220706070350.1703384-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6338574..f1b84e2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2808,7 +2808,7 @@ static void bio_set_ioprio(struct bio *bio)
 void blk_mq_submit_bio(struct bio *bio)
 {
 	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
-	struct blk_plug *plug = blk_mq_plug(q, bio);
+	struct blk_plug *plug = blk_mq_plug(bio);
 	const int is_sync = op_is_sync(bio->bi_opf);
 	struct request *rq;
 	unsigned int nr_segs = 1;