Set docker image tag for OpenContrail in defaults

Change-Id: Ia5eca39b401b6b72c24f904aa84c875a7f5b2629
Related-PROD: PROD-28995
diff --git a/opencontrail/control/single4_0.yml b/opencontrail/control/single4_0.yml
index 9c11443..d0573e9 100644
--- a/opencontrail/control/single4_0.yml
+++ b/opencontrail/control/single4_0.yml
@@ -9,10 +9,9 @@
     opencontrail_kafka_log_dir: '/usr/share/kafka/logs'
     opencontrail_version: 4.0
     linux_repo_contrail_component: oc40
-    opencontrail_image_tag: latest
-    opencontrail_analytics_image: ${_param:mcp_docker_registry}/opencontrail-${_param:linux_repo_contrail_component}/opencontrail-analytics:${_param:opencontrail_image_tag}
-    opencontrail_analyticsdb_image: ${_param:mcp_docker_registry}/opencontrail-${_param:linux_repo_contrail_component}/opencontrail-analyticsdb:${_param:opencontrail_image_tag}
-    opencontrail_controller_image: ${_param:mcp_docker_registry}/opencontrail-${_param:linux_repo_contrail_component}/opencontrail-controller:${_param:opencontrail_image_tag}
+    opencontrail_analytics_image: ${_param:mcp_docker_registry}/opencontrail-${_param:linux_repo_contrail_component}/opencontrail-analytics:${_param:opencontrail_docker_image_tag}
+    opencontrail_analyticsdb_image: ${_param:mcp_docker_registry}/opencontrail-${_param:linux_repo_contrail_component}/opencontrail-analyticsdb:${_param:opencontrail_docker_image_tag}
+    opencontrail_controller_image: ${_param:mcp_docker_registry}/opencontrail-${_param:linux_repo_contrail_component}/opencontrail-controller:${_param:opencontrail_docker_image_tag}
     opencontrail_controller_container_name: opencontrail_controller_1
     opencontrail_analytics_container_name: opencontrail_analytics_1
     opencontrail_analyticsdb_container_name: opencontrail_analyticsdb_1