blkcg: fix memleak for iolatency

Normally, blkcg_iolatency_exit() will free related memory in iolatency
when cleanup queue. But if blk_throtl_init() return error and queue init
fail, blkcg_iolatency_exit() will not do that for us. Then it cause
memory leak.

Fixes: d7067512 ("block: introduce blk-iolatency io controller")
Signed-off-by: NYufen Yu <yuyufen@huawei.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -1152,13 +1152,15 @@ int blkcg_init_queue(struct request_queue *q)
 	if (preloaded)
 		radix_tree_preload_end();
 
-	ret = blk_iolatency_init(q);
+	ret = blk_throtl_init(q);
 	if (ret)
 		goto err_destroy_all;
 
-	ret = blk_throtl_init(q);
-	if (ret)
+	ret = blk_iolatency_init(q);
+	if (ret) {
+		blk_throtl_exit(q);
 		goto err_destroy_all;
+	}
 	return 0;
 
 err_destroy_all: