Add pull_docker_registry

Change-Id: Ic255aa0b800012c52c478dcd5228a598b4ff3b9b
diff --git a/roles/onos-cord-install/templates/docker-compose.yml.j2 b/roles/onos-cord-install/templates/docker-compose.yml.j2
index 704f83f..40f4665 100644
--- a/roles/onos-cord-install/templates/docker-compose.yml.j2
+++ b/roles/onos-cord-install/templates/docker-compose.yml.j2
@@ -4,7 +4,7 @@
 services:
 
    xos-onos:
-      image: xos/onos:{{ deploy_docker_tag }}
+      image: xos/onos:{{ pull_docker_tag }}
       ports:
        - "6654:6653"
        - "8102:8101"