notification_driver is deprecated to driver

TrivialFix
https://review.openstack.org/#/c/249508/

Change-Id: I18599c7221272279dfc2e9f5b297af09faff5c3b
diff --git a/lib/cinder b/lib/cinder
index 9ca8109..144f41b 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -299,7 +299,7 @@
     fi
 
     if is_service_enabled ceilometer; then
-        iniset $CINDER_CONF DEFAULT notification_driver "messaging"
+        iniset $CINDER_CONF oslo_messaging_notifications driver "messaging"
     fi
 
     if is_service_enabled tls-proxy; then