Neutron-legacy: Remove LINUXNET_VIF_DRIVER option

A value is never assigned, and it ends up in the nova.conf file as:

linuxnet_interface_driver =

So, let's delete it.

Change-Id: Ibc270ce6ee622eee871df1f8c11f21e8be8280ee

Author: sc68cal

lib/neutron-legacy

@@ -488,7 +488,6 @@ function create_nova_conf_neutron {
     # optionally set options in nova_conf
     neutron_plugin_create_nova_conf
 
-    iniset $NOVA_CONF DEFAULT linuxnet_interface_driver "$LINUXNET_VIF_DRIVER"
     if is_service_enabled q-meta; then
         iniset $NOVA_CONF neutron service_metadata_proxy "True"
     fi