ceph-common: specify file path for repo key

Signed-off-by: Alfredo Deza <adeza@redhat.com>

Resolves: rhbz#1339068

tasks/installs/install_rh_storage_on_debian.yml

@@ -5,7 +5,7 @@
 # intelligent way to determine the location of the key.
 - name: install the rh ceph storage repository key
   apt_key:
-    data: "{{ ceph_stable_rh_storage_repository_path }}/MON/release.asc"
+    file: "{{ ceph_stable_rh_storage_repository_path }}/MON/release.asc"
     state: present
   when:
     - ceph_stable_rh_storage