Fixed AttributeError in l2pop.delete_port_postcommit

The error sneaked in with Ib6e59ab3405857d3ed4d82df1a80800089c3f06e
where is_ha_router_port expects a NeutronContext object but we still
pass PortContext instead.

Change-Id: I593af5d050de00ddea7d758007d9856c4b97695f
Closes-Bug: #1703938

neutron/plugins/ml2/drivers/l2pop/mech_driver.py

@@ -76,7 +76,7 @@ class L2populationMechanismDriver(api.MechanismDriver):
         fdb_entries = self._get_agent_fdb(
             plugin_context, context.bottom_bound_segment, port, agent_host)
         if fdb_entries and l3_hamode_db.is_ha_router_port(
-                context, port['device_owner'], port['device_id']):
+                plugin_context, port['device_owner'], port['device_id']):
             session = db_api.get_reader_session()
             network_id = port['network_id']
             other_fdb_ports = self._get_ha_port_agents_fdb(

neutron/tests/unit/plugins/ml2/drivers/l2pop/test_mech_driver.py

@@ -1146,6 +1146,14 @@ class TestL2PopulationRpcTestCase(test_plugin.Ml2PluginV2TestCase):
                     self.driver.get_network(
                         self.context, p['port']['network_id']),
                     models.PortBinding(), bindings)
+                fdbs = {
+                    p['port']['network_id']: {
+                        'segment_id': 'fakeid',
+                        'ports': {},
+                    }
+                }
+                mock.patch.object(
+                    l2pop_mech, '_get_agent_fdb', return_value=fdbs).start()
                 # The point is to provide coverage and to assert that
                 # no exceptions are raised.
                 l2pop_mech.delete_port_postcommit(port_context)