cgroup: add missing skcd->no_refcnt check in cgroup_sk_clone()

Add skcd->no_refcnt check which is missed when backporting
ad0f75e5 ("cgroup: fix cgroup_sk_alloc() for sk_clone_lock()").

This patch is needed in stable-4.9, stable-4.14 and stable-4.19.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

kernel/cgroup/cgroup.c

@@ -5957,6 +5957,8 @@ void cgroup_sk_clone(struct sock_cgroup_data *skcd)
 {
 	/* Socket clone path */
 	if (skcd->val) {
+		if (skcd->no_refcnt)
+			return;
 		/*
 		 * We might be cloning a socket which is left in an empty
 		 * cgroup and the cgroup might have already been rmdir'd.