net: Convert sysctl_core_ops

These pernet_operations register and destroy sysctl
directory, and it's not interesting for foreign
pernet_operations.

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

net/core/sysctl_net_core.c

@@ -572,6 +572,7 @@ static __net_exit void sysctl_core_net_exit(struct net *net)
 static __net_initdata struct pernet_operations sysctl_core_ops = {
 	.init = sysctl_core_net_init,
 	.exit = sysctl_core_net_exit,
+	.async = true,
 };
 
 static __init int sysctl_core_init(void)