Change rgw frontend interface

Change the rgw frontend interface (from storage_interface to
api_interface) to make it consistent with the one specified in the
haproxy configuration.

Closes-Bug: #1603885
Change-Id: I8537f05575382faeac3ab915feaaad4af9b29565

ansible/roles/ceph/templates/ceph.conf.j2

@@ -24,5 +24,5 @@ mon compact on start = true
 host = {{ hostvars[inventory_hostname]['ansible_' + storage_interface]['ipv4']['address'] }}
 keyring = /etc/ceph/ceph.client.radosgw.keyring
 log file = /var/log/kolla/ceph/client.radosgw.gateway.log
-rgw frontends = civetweb port={{ hostvars[inventory_hostname]['ansible_' + storage_interface]['ipv4']['address'] }}:{{ rgw_port }}
+rgw frontends = civetweb port={{ hostvars[inventory_hostname]['ansible_' + api_interface]['ipv4']['address'] }}:{{ rgw_port }}
 {% endif %}