ceph-mds: fix MDS conditions

We don't need to set is_systemd when we are applying a configuration for
a sysvinit init.

Signed-off-by: Sébastien Han <seb@redhat.com>

roles/ceph-mds/tasks/pre_requisite.yml

@@ -76,7 +76,7 @@
     - done
     - sysvinit
   changed_when: false
-  when: use_systemd
+  when: not use_systemd
 
 - name: enable systemd unit file for mds instance (for or after infernalis)
   file:
@@ -103,7 +103,7 @@
     args: mds.{{ mds_name }}
   changed_when: false
   when:
-    use_systemd and
+    not use_systemd and
     is_before_infernalis
 
 - name: start and add that the metadata service to the init sequence (systemd after hammer)