[NET] NETNS: Omit seq_net_private->net without CONFIG_NET_NS.

Without CONFIG_NET_NS, no namespace other than &init_net exists,
no need to store net in seq_net_private.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 20a3d8e..d810cff 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -2355,7 +2355,7 @@
 {
 	struct ifmcaddr6 *im = NULL;
 	struct igmp6_mc_iter_state *state = igmp6_mc_seq_private(seq);
-	struct net *net = state->p.net;
+	struct net *net = seq_file_net(seq);
 
 	state->idev = NULL;
 	for_each_netdev(net, state->dev) {
@@ -2486,7 +2486,7 @@
 	struct ip6_sf_list *psf = NULL;
 	struct ifmcaddr6 *im = NULL;
 	struct igmp6_mcf_iter_state *state = igmp6_mcf_seq_private(seq);
-	struct net *net = state->p.net;
+	struct net *net = seq_file_net(seq);
 
 	state->idev = NULL;
 	state->im = NULL;