Specify node_network_info is a dict

If we don't set this to a dict, the bifrost_configdrives_dynamic
fail if node_network_info is empty, since it converts it to '',
instead of {}.

Change-Id: Ic6db4288fbb7945525cf2d7dd4cc8a4afbf80565

playbooks/library/network_metadata.py

@@ -34,7 +34,7 @@ def main():
         vlan_id=dict(required=False),
         network_mtu=dict(required=False),
         nics=dict(required=False, type='list'),
-        node_network_info=dict(required=False)
+        node_network_info=dict(required=False, type='dict')
     )
 
     module = AnsibleModule(argument_spec)

playbooks/roles/bifrost-configdrives-dynamic/tasks/main.yml

@@ -48,7 +48,7 @@
     vlan_id: "{{ vlan_id | default('') }}"
     network_mtu: "{{ network_mtu | default('1500') }}"
     nics: "{{ nics | default(omit) }}"
-    node_network_info: "{{ node_network_info | default('') }}"
+    node_network_info: "{{ node_network_info | default({}) }}"
   when: addressing_mode is undefined or "dhcp" not in addressing_mode
 - name: "Place network info template in each openstack/latest folder"
   template: