net: Convert dccp_v6_ops

These pernet_operations looks similar to dccp_v4_ops,
and they are also safe to be marked as async.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/ipv6.c

@@ -1116,6 +1116,7 @@ static struct pernet_operations dccp_v6_ops = {
 	.init   = dccp_v6_init_net,
 	.exit   = dccp_v6_exit_net,
 	.exit_batch = dccp_v6_exit_batch,
+	.async	= true,
 };
 
 static int __init dccp_v6_init(void)