Fix condition of placement image build

This should fix placement image build if nova is disabled but zun is
enabled.

Change-Id: I238aeefefa88dd584ce61ac9eb52d50552336ed0

ansible/group_vars/all/kolla

@@ -216,7 +216,7 @@ overcloud_container_image_regex_map:
   - regex: panko
     enabled: "{{ kolla_enable_panko | bool }}"
   - regex: placement
-    enabled: "{{ kolla_enable_nova | bool }}"
+    enabled: "{{ kolla_enable_placement | bool }}"
   - regex: prometheus
     enabled: "{{ kolla_enable_prometheus | bool }}"
   - regex: qdrouterd