[ONOS-6064] Support for IPv6 tunnel (currently supported in Open vSwitch 2.6.0)

Change-Id: Iff47f110ee25b4a65830c939bbd540350e07575d
diff --git a/openflow_input/oxm_nicira_tun b/openflow_input/oxm_nicira_tun
index ae2575f..c3d0e01 100644
--- a/openflow_input/oxm_nicira_tun
+++ b/openflow_input/oxm_nicira_tun
@@ -54,6 +54,12 @@
     of_ipv4_t value_mask;
 };
 
+// Nicira extension for tun_ipv6_dst
+struct of_oxm_tunnel_ipv6_dst : of_oxm {
+    uint32_t type_len == 0x0001dc10;
+    of_ipv6_t value;
+};
+
 // Nicira extension for tun_flags (104)
 struct of_oxm_tun_flags : of_oxm {
     uint32_t type_len == 0x0001d002;