net: Convert nfnl_acct_ops

These pernet_operations look closed in themself,
and there are no other users of net::nfnl_acct_list
outside. They are safe to be executed for several
net namespaces in parallel.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/nfnetlink_acct.c

@@ -515,6 +515,7 @@ static void __net_exit nfnl_acct_net_exit(struct net *net)
 static struct pernet_operations nfnl_acct_ops = {
         .init   = nfnl_acct_net_init,
         .exit   = nfnl_acct_net_exit,
+	.async	= true,
 };
 
 static int __init nfnl_acct_init(void)