netfilter: nfnetlink_queue: Unregister pernet subsys in case of init failure

commit 639e077b upstream.

Commit 3bfe0498 ("netfilter: nfnetlink_{log,queue}:
Register pernet in first place") reorganised the initialisation
order of the pernet_subsys to avoid "use-before-initialised"
condition. However, in doing so the cleanup logic in nfnetlink_queue
got botched in that the pernet_subsys wasn't cleaned in case
nfnetlink_subsys_register failed. This patch adds the necessary
cleanup routine call.

Fixes: 3bfe0498 ("netfilter: nfnetlink_{log,queue}: Register pernet in first place")
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[ kamal: backport to 4.2-stable: appled to nfnetlink_queue_core.c ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

net/netfilter/nfnetlink_queue_core.c

@@ -1392,6 +1392,7 @@ static int __init nfnetlink_queue_init(void)
 
 cleanup_netlink_notifier:
 	netlink_unregister_notifier(&nfqnl_rtnl_notifier);
+	unregister_pernet_subsys(&nfnl_queue_net_ops);
 out:
 	return status;
 }