neutron: use non-deprecated notification_driver

Neutron is now using oslo.messaging so it should be
using 'messaging' as its notification driver and not the now deprecated
full python path to the oslo-incubator notification driver.

Change-Id: Ie4a4020e59473473ad62059c66507f5b73b93375
diff --git a/lib/neutron b/lib/neutron
index f72ee59..22d4f37 100644
--- a/lib/neutron
+++ b/lib/neutron
@@ -799,7 +799,7 @@
 }
 
 function _configure_neutron_ceilometer_notifications {
-    iniset $NEUTRON_CONF DEFAULT notification_driver neutron.openstack.common.notifier.rpc_notifier
+    iniset $NEUTRON_CONF DEFAULT notification_driver messaging
 }
 
 function _configure_neutron_lbaas {