Fix nuage check.

roles/openshift_common/tasks/main.yml

@@ -4,8 +4,8 @@
   when: openshift_use_openshift_sdn | default(false) | bool and openshift_use_flannel | default(false) | bool
 
 - fail:
-   msg: Nuage sdn can not be used with openshift sdn
-  when: openshift_use_openshift_sdn | default(false) | bool and openshift_use_nuage | default(false) | bool
+   msg: Nuage sdn can not be used with openshift sdn, set openshift_use_openshift_sdn=false if you want to use nuage
+  when: openshift_use_openshift_sdn | default(true) | bool and openshift_use_nuage | default(false) | bool
 
 - fail:
    msg: Nuage sdn can not be used with flannel