blk-mq: Invert check in blk_mq_update_nr_requests()

It's easier to read:

if (x)
	X;
else
	Y;

over:

if (!x)
	Y;
else
	X;

No functional change intended.
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/1633429419-228500-5-git-send-email-john.garry@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -3622,18 +3622,18 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 		 * If we're using an MQ scheduler, just update the scheduler
 		 * queue depth. This is similar to what the old code would do.
 		 */
-		if (!hctx->sched_tags) {
-			ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
-							false);
-		} else {
+		if (hctx->sched_tags) {
 			ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
-							nr, true);
+						      nr, true);
 			if (blk_mq_is_sbitmap_shared(set->flags)) {
 				hctx->sched_tags->bitmap_tags =
 					&q->sched_bitmap_tags;
 				hctx->sched_tags->breserved_tags =
 					&q->sched_breserved_tags;
 			}
+		} else {
+			ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
+						      false);
 		}
 		if (ret)
 			break;