Add missing [privsep_entrypoint]/helper_command

Closes-Bug: ATMOSPHERE-648
Change-Id: I12243527ad763bb249195220093717d68de050f6
diff --git a/roles/cinder/vars/main.yml b/roles/cinder/vars/main.yml
index 4917bd9..ef3d6cd 100644
--- a/roles/cinder/vars/main.yml
+++ b/roles/cinder/vars/main.yml
@@ -52,6 +52,8 @@
         pool_timeout: 30
       oslo_messaging_notifications:
         driver: noop
+      privsep_osbrick:
+        helper_command: sudo cinder-rootwrap /etc/cinder/rootwrap.conf privsep-helper --config-file /etc/cinder/cinder.conf
   manifests:
     ingress_api: false
     job_clean: false