kernel: nf_conntrack_rtcache: fix WARNING on rmmod

Fixes b7c58a1ee ("kernel: nf_conntrack_rtcache: fix cleanup on netns
delete and rmmod")

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
(cherry picked from commit b3779e920e)

target/linux/generic/backport-4.14/020-backport_netfilter_rtcache.patch

@@ -127,7 +127,7 @@ Signed-off-by: Florian Westphal <fw@strlen.de>
  # netlink interface for nf_conntrack
 --- /dev/null
 +++ b/net/netfilter/nf_conntrack_rtcache.c
-@@ -0,0 +1,430 @@
+@@ -0,0 +1,428 @@
 +/* route cache for netfilter.
 + *
 + * (C) 2014 Red Hat GmbH
@@ -528,8 +528,6 @@ Signed-off-by: Florian Westphal <fw@strlen.de>
 +
 +	unregister_netdevice_notifier(&nf_rtcache_notifier);
 +	unregister_pernet_subsys(&rtcache_ops_net_ops);
-+	for_each_net(net)
-+		nf_unregister_net_hooks(net, rtcache_ops, ARRAY_SIZE(rtcache_ops));
 +
 +	synchronize_net();
 +