net: Convert simple pernet_operations

These pernet_operations make pretty simple actions
like variable initialization on init, debug checks
on exit, and so on, and they obviously are able
to be executed in parallel with any others:

vrf_net_ops
lockd_net_ops
grace_net_ops
xfrm6_tunnel_net_ops
kcm_net_ops
tcf_net_ops

Signed-off-by: Kirill Tkhai <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

net/kcm/kcmsock.c

@@ -2015,6 +2015,7 @@ static struct pernet_operations kcm_net_ops = {
 	.exit = kcm_exit_net,
 	.id   = &kcm_net_id,
 	.size = sizeof(struct kcm_net),
+	.async = true,
 };
 
 static int __init kcm_init(void)