Disable nova-compute when enable_ironic is yes

Change-Id: Icb77da008247609e9e1ce45770c9925d9b416739
Closes-Bug: #1665905

ansible/roles/nova/defaults/main.yml

@@ -112,7 +112,7 @@ nova_services:
     group: "compute"
     image: "{{ nova_compute_image_full }}"
     privileged: True
-    enabled: "{{ not enable_nova_fake | bool or not enable_ironic | bool }}"
+    enabled: "{{ not enable_nova_fake | bool and not enable_ironic | bool }}"
     volumes:
       - "{{ node_config_directory }}/nova-compute/:{{ container_config_directory }}/:ro"
       - "/etc/localtime:/etc/localtime:ro"