Define openstack version for trusty in contrail40

Ocata is not available for trusty. So for trusty
nodes (ntw and nal) use mitaka as openstack version

Change-Id: Ied2a5119e307eba08fceb98ff0cf6236a7b7fb5c
diff --git a/classes/cluster/os-ha-contrail-40/opencontrail/control.yml b/classes/cluster/os-ha-contrail-40/opencontrail/control.yml
index c3a531d..4a4fab2 100644
--- a/classes/cluster/os-ha-contrail-40/opencontrail/control.yml
+++ b/classes/cluster/os-ha-contrail-40/opencontrail/control.yml
@@ -20,6 +20,7 @@
 - cluster.os-ha-contrail-40
 parameters:
   _param:
+    openstack_version: mitaka
     keepalived_vip_interface: ${_param:opencontrail_control_interface_name}
     cluster_vip_address: ${_param:opencontrail_control_address}
     cluster_local_address: ${_param:single_address}