Unset gateway for data net

- Do not set gateway for data net to avoid duplication
  of default routes on nodes

Related-PROD: Related-PROD: KUBV-57

Change-Id: I4a8ce135c75a7780f459b7c7df8d137a85a92949
diff --git a/hco/top.yaml b/hco/top.yaml
index 6998956..59aeaeb 100644
--- a/hco/top.yaml
+++ b/hco/top.yaml
@@ -83,6 +83,7 @@
       network: { get_resource: data_network }
       enable_dhcp: false
       cidr: { get_param: data_network_cidr }
+      gateway_ip: ~
 
   masters:
     type: OS::Heat::ResourceGroup