ubi: block: fix memleak in ubiblock_create()

If idr_alloc() fails, dev->gd will be put after goto out_cleanup_disk in
ubiblock_create(), but dev->gd has not been assigned yet at this time, and
'gd' will not be put anymore. Fix it by putting 'gd' directly.
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/block.c

@@ -434,7 +434,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	list_del(&dev->list);
 	idr_remove(&ubiblock_minor_idr, gd->first_minor);
 out_cleanup_disk:
-	put_disk(dev->gd);
+	put_disk(gd);
 out_free_tags:
 	blk_mq_free_tag_set(&dev->tag_set);
 out_free_dev: