net: Convert sunrpc_net_ops

These pernet_operations look similar to rpcsec_gss_net_ops,
they just create and destroy another caches. So, they also
can be async.

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

net/sunrpc/sunrpc_syms.c

@@ -79,6 +79,7 @@ static struct pernet_operations sunrpc_net_ops = {
 	.exit = sunrpc_exit_net,
 	.id = &sunrpc_net_id,
 	.size = sizeof(struct sunrpc_net),
+	.async = true,
 };
 
 static int __init