openstack: use ceph_keyring_permissions by default

Otherwise this task fails if no permission is set on the item.
Previously the code omited the mode parameter if it was not set, but
this was lost with commit ab370b6a

.
Signed-off-by: Gaudenz Steinlin <gaudenz.steinlin@cloudscale.ch>

roles/ceph-osd/tasks/openstack_config.yml

@@ -49,7 +49,7 @@
         content: "{{ item.0.stdout + '\n' }}"
         owner: "{{ ceph_uid if containerized_deployment | bool else 'ceph' }}"
         group: "{{ ceph_uid if containerized_deployment | bool else 'ceph' }}"
-        mode: "{{ item.0.item.mode }}"
+        mode: "{{ item.0.item.mode | default(ceph_keyring_permissions) }}"
       with_nested:
         - "{{ _osp_keys.results }}"
         - "{{ groups[mon_group_name] }}"