tcp: Like icmp use register_pernet_subsys

To remove the possibility of packets flying around when network
devices are being cleaned up use reisger_pernet_subsys instead of
register_pernet_device.
Signed-off-by: NEric W. Biederman <ebiederm@aristanetworks.com>
Acked-by: NDenis V. Lunev <den@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_ipv4.c

@@ -2443,7 +2443,7 @@ static struct pernet_operations __net_initdata tcp_sk_ops = {
 void __init tcp_v4_init(void)
 {
 	inet_hashinfo_init(&tcp_hashinfo);
-	if (register_pernet_device(&tcp_sk_ops))
+	if (register_pernet_subsys(&tcp_sk_ops))
 		panic("Failed to create the TCP control socket.\n");
 }