net: Convert iptable_security_net_ops

These pernet_operations unregister net::ipv4::iptable_security table.
Another net/pernet_operations do not send ipv4 packets to foreign
net namespaces. So, we mark them async.
Signed-off-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/netfilter/iptable_security.c

@@ -76,6 +76,7 @@ static void __net_exit iptable_security_net_exit(struct net *net)
 
 static struct pernet_operations iptable_security_net_ops = {
 	.exit = iptable_security_net_exit,
+	.async = true,
 };
 
 static int __init iptable_security_init(void)