net: Drop pernet_operations::async

Synchronous pernet_operations are not allowed anymore.
All are asynchronous. So, drop the structure member.

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

net/netlink/af_netlink.c

@@ -253,7 +253,6 @@ static struct pernet_operations netlink_tap_net_ops = {
 	.exit = netlink_tap_exit_net,
 	.id   = &netlink_tap_net_id,
 	.size = sizeof(struct netlink_tap_net),
-	.async = true,
 };
 
 static bool netlink_filter_tap(const struct sk_buff *skb)
@@ -2726,7 +2725,6 @@ static void __init netlink_add_usersock_entry(void)
 static struct pernet_operations __net_initdata netlink_net_ops = {
 	.init = netlink_net_init,
 	.exit = netlink_net_exit,
-	.async = true,
 };
 
 static inline u32 netlink_hash(const void *data, u32 len, u32 seed)

net/netlink/genetlink.c

@@ -1035,7 +1035,6 @@ static void __net_exit genl_pernet_exit(struct net *net)
 static struct pernet_operations genl_pernet_ops = {
 	.init = genl_pernet_init,
 	.exit = genl_pernet_exit,
-	.async = true,
 };
 
 static int __init genl_init(void)