Fix CephExternalMultiConfig using tripleo_ceph_client

When using the tripleo_ceph_client role to configure ceph clients,
the wrong variable named was used to pass info related to any
clusters specified by CephExternalMultiConfig. While the initial
tripleo_ceph_client patch set used a variable named "dcn," the
name was changed to "multiple" [1].

5242cc4774/tripleo_ansible/roles/tripleo_ceph_client/tasks/main.yml (L63)

Change-Id: I77100adf1cf62c193ae2393a1401ba4a3f2d5e13

deployment/ceph-ansible/ceph-base.yaml

@@ -721,7 +721,7 @@ outputs:
               name: tripleo client role
               vars:
                 tripleo_ceph_client_config_home: {get_param: CephConfigPath}
-                dcn: "{{ item }}"
+                multiple: "{{ item }}"
               loop: "{{ ceph_external_multi_config }}"
               when:
                 - ceph_external_multi_config is defined

deployment/cephadm/ceph-client.yaml

@@ -133,7 +133,7 @@ outputs:
                 name: tripleo client role
                 vars:
                   tripleo_ceph_client_config_home: {get_param: CephConfigPath}
-                  dcn: "{{ item }}"
+                  multiple: "{{ item }}"
                 loop: "{{ ceph_external_multi_config }}"
                 when:
                   - ceph_external_multi_config is defined