net: Convert synproxy_net_ops

These pernet_operations create and destroy /proc entries
and allocate extents to template ct, which depend on global
nf_ct_ext_types[] array. So, we are able to mark them async.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/nf_synproxy_core.c

@@ -398,6 +398,7 @@ static struct pernet_operations synproxy_net_ops = {
 	.exit		= synproxy_net_exit,
 	.id		= &synproxy_net_id,
 	.size		= sizeof(struct synproxy_net),
+	.async		= true,
 };
 
 static int __init synproxy_core_init(void)