vxlan: add ipv6 route short circuit support

route short circuit only has IPv4 part, this patch adds
the IPv6 part. nd_tbl will be needed.

Cc: David S. Miller <davem@davemloft.net>
Cc: David Stevens <dlstevens@us.ibm.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 0c9c22f..1996a7c 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -815,6 +815,7 @@
 	.ipv6_sock_mc_drop = ipv6_sock_mc_drop,
 	.ipv6_dst_lookup = ip6_dst_lookup,
 	.udpv6_encap_enable = udpv6_encap_enable,
+	.nd_tbl	= &nd_tbl,
 };
 
 static int __init inet6_init(void)