Ensure that subnet update does not creat RPC client
Ensure that subnet update does not creat RPC client

Commit fc7cae844cb783887b8a8eb4d9c3286116d740e6 would create
the notification class each time that the subnet update is
invoked.

Change-Id: Ie62f4bc4f152cb346d4e6de77b732a87ab6f2f28
Closes-bug: #1661181

openstack/neutron,openstack/neutron,noironetworks/neutron,eayunstack/neutron,openstack/neutron,noironetworks/neutron,mahak/neutron,mahak/neutron,mahak/neutron,eayunstack/neutron,huntxu/neutron,huntxu/neutron