Ensure service is enabled

With older tripleo versions, we did disable the service since we were
using ntpd.
If we upgrade from a version using ntpd, the chronyd service won't be
active upon reboot.

Change-Id: Ic59374afdf5ace02ba8243f5163d0950e527ec52
Closes-Bug: #1835368

tasks/config.yml

@@ -11,6 +11,7 @@
 
 - name: Ensure chronyd is running
   service:
+    enabled: yes
     name: "{{ chrony_service_name }}"
     state: "{{ chrony_service_state|default('started') }}"
   when: chrony_manage_service|bool