block: put dev->kobj in blk_register_queue fail path

kernel needs to kobject_put on dev->kobj if elv_register_queue fails.
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Nikanth Karthikesan <knikanth@suse.de>
Cc: David Teigland <teigland@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

block/blk-sysfs.c

@@ -511,6 +511,7 @@ int blk_register_queue(struct gendisk *disk)
 		kobject_uevent(&q->kobj, KOBJ_REMOVE);
 		kobject_del(&q->kobj);
 		blk_trace_remove_sysfs(disk_to_dev(disk));
+		kobject_put(&dev->kobj);
 		return ret;
 	}