[NETNS][IPV6] ndisc - make socket control per namespace

Make ndisc socket control per namespace.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: Benjamin Thery <benjamin.thery@bull.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 90e6e24..b773256 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -51,5 +51,6 @@
 	struct fib_rules_ops    *fib6_rules_ops;
 #endif
 	struct sock		**icmp_sk;
+	struct sock             *ndisc_sk;
 };
 #endif