Fix an undefined variable bug for venus deployment

The external_protocol variable does not exist, resulting in an error
during the venus deployment process. This commit will fix that.

Closes-Bug: #2029353

Change-Id: I2d983eecd8861689fdab7d60bdb9dd34ea0c159e

ansible/roles/venus/defaults/main.yml

@@ -95,7 +95,7 @@ venus_manager_extra_volumes: "{{ venus_extra_volumes }}"
 # OpenStack
 ####################
 venus_internal_endpoint: "{{ venus_internal_fqdn | kolla_url(internal_protocol, venus_api_port) }}"
-venus_public_endpoint: "{{ venus_external_fqdn | kolla_url(external_protocol, venus_api_port) }}"
+venus_public_endpoint: "{{ venus_external_fqdn | kolla_url(public_protocol, venus_api_port) }}"
 
 venus_logging_debug: "{{ openstack_logging_debug }}"