Fix overwrite for kubernetes images

Now uses overrides.yml instead of overwrite.yml

Change-Id: Ia16e8f1cb3c70261599dc4cf3fcce893442d8f24
diff --git a/classes/cluster/virtual-mcp11-dvr/init.yml b/classes/cluster/virtual-mcp11-dvr/init.yml
index ad3eba8..56dc18d 100644
--- a/classes/cluster/virtual-mcp11-dvr/init.yml
+++ b/classes/cluster/virtual-mcp11-dvr/init.yml
@@ -12,7 +12,7 @@
 - cluster.virtual-mcp11-dvr.infra
 - cluster.virtual-mcp11-dvr.openstack
 - cluster.virtual-mcp11-dvr.stacklight
-- cluster.overwrite
+- cluster.overrides
 parameters:
   _param:
     cluster_domain: virtual-mcp11-dvr.local