[NETNS]: Inet control socket should not hold a namespace.

This is a generic requirement, so make inet_ctl_sock_create namespace
aware and create a inet_ctl_sock_destroy wrapper around
sk_release_kernel.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_ipv4.c

@@ -2491,7 +2491,7 @@ struct proto tcp_prot = {
 void __init tcp_v4_init(void)
 {
 	if (inet_ctl_sock_create(&tcp_sock, PF_INET, SOCK_RAW,
-				 IPPROTO_TCP) < 0)
+				 IPPROTO_TCP, &init_net) < 0)
 		panic("Failed to create the TCP control socket.\n");
 }