Change how ovn mech driver checks if vlan transparency is supported

Previously ovn mech driver was supporting vlan transparency for all
types of networks.
But it's not that easy and for flat networks it doesn't work (at least
for now). So this patch changes the way how check_vlan_transparency()
method is implemented in ovn mech_driver.

Change-Id: Ie5357980f70e4853f320785258cbb6bb603cc104

neutron/plugins/ml2/drivers/ovn/mech_driver/mech_driver.py

@@ -23,6 +23,7 @@ import types
 
 import netaddr
 from neutron_lib.api.definitions import portbindings
+from neutron_lib.api.definitions import provider_net
 from neutron_lib.api.definitions import segment as segment_def
 from neutron_lib.callbacks import events
 from neutron_lib.callbacks import registry
@@ -155,7 +156,14 @@ class OVNMechanismDriver(api.MechanismDriver):
 
     def check_vlan_transparency(self, context):
         """OVN driver vlan transparency support."""
-        return True
+        vlan_transparency_network_types = [
+            const.TYPE_LOCAL,
+            const.TYPE_GENEVE,
+            const.TYPE_VXLAN,
+            const.TYPE_VLAN
+        ]
+        return (context.current.get(provider_net.NETWORK_TYPE)
+                in vlan_transparency_network_types)
 
     def _setup_vif_port_bindings(self):
         self.supported_vnic_types = [portbindings.VNIC_NORMAL,