net: Convert xfrm6_net_ops

These pernet_operations create sysctl tables and
initialize net::xfrm.xfrm6_dst_ops used for routing.
It doesn't look like another pernet_operations send
ipv6 packets to foreign net namespaces, so it should
be safe to mark the pernet_operations as async.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/xfrm6_policy.c

@@ -395,6 +395,7 @@ static void __net_exit xfrm6_net_exit(struct net *net)
 static struct pernet_operations xfrm6_net_ops = {
 	.init	= xfrm6_net_init,
 	.exit	= xfrm6_net_exit,
+	.async	= true,
 };
 
 int __init xfrm6_init(void)