Stop configuring neutron to enforce DHCP MTU option
Stop configuring neutron to enforce DHCP MTU option

Since Mitaka, Neutron does the right job to calculate and advertise
correct MTU to instances, out of the box.

Change-Id: I30e1fae85cb8b5154e59dac54f3f4356979456de

mahak/packstack,openstack/packstack,stackforge/packstack,stackforge/packstack,fr34k8/packstack,fr34k8/packstack,openstack/packstack,stackforge/packstack,fr34k8/packstack,openstack/packstack,mahak/packstack,mahak/packstack