Skip vlan/bp on flat networks on 3party gateways

Do not create vlan/bridge port on VSD for flat neutron
networks when orchestrating direct ports. Current netconf
integration with Cisco switches does not support native vlan.
This patchset will allow sriov deployments with trunks.
Note however, there will be no connectivity in parent flat network.

Change-Id: I9bbc1779be019e085e198e33116d5a48459b3721
Partial-Bug: OPENSTACK-2835

nuage_neutron/plugins/sriov/mech_nuage.py

@@ -384,6 +384,12 @@ def _create_nuage_bridge_vport(self, port_dict):
                     raise exceptions.NuageBadRequest(msg=msg)
                 gw = gws[0]
 
+                # gridinv: following code should be removed when
+                # we have proper support of native vlan on cisco/netconf
+                if ('NETCONF_THIRDPARTY' in gw['gw_type'] and
+                        segmentation_id == 0):
+                    return
+
                 port_id = gwport['port_id']
                 params = {
                     'gatewayport': port_id,