[NETNS][DCCPV6]: Move the dccp_v6_ctl_sk on the struct net.

And replace all its usage with init_net's socket.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/dccp.h

@@ -5,6 +5,7 @@ struct sock;
 
 struct netns_dccp {
 	struct sock *v4_ctl_sk;
+	struct sock *v6_ctl_sk;
 };
 
 #endif