dm: drop unnecessary assignment of md->queue

md->queue and q are the same thing in dm_old_init_request_queue() and
dm_mq_init_request_queue().

Also drop the temporary 'struct request_queue *q' in
dm_old_init_request_queue().
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm.c

@@ -2654,17 +2654,13 @@ static void dm_old_init_rq_based_worker_thread(struct mapped_device *md)
  */
 static int dm_old_init_request_queue(struct mapped_device *md)
 {
-	struct request_queue *q = NULL;
-
 	/* Fully initialize the queue */
-	q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
-	if (!q)
+	if (!blk_init_allocated_queue(md->queue, dm_request_fn, NULL))
 		return -EINVAL;
 
 	/* disable dm_request_fn's merge heuristic by default */
 	md->seq_rq_merge_deadline_usecs = 0;
 
-	md->queue = q;
 	dm_init_normal_md_queue(md);
 	blk_queue_softirq_done(md->queue, dm_softirq_done);
 	blk_queue_prep_rq(md->queue, dm_old_prep_fn);
@@ -2783,7 +2779,6 @@ static int dm_mq_init_request_queue(struct mapped_device *md,
 		err = PTR_ERR(q);
 		goto out_tag_set;
 	}
-	md->queue = q;
 	dm_init_md_queue(md);
 
 	/* backfill 'mq' sysfs registration normally done in blk_register_queue */