Remove NOVA_VIF_DRIVER variable

Commit 7561c8ded211d53e8745d1420a73b82bd0fc35cf removed the
libvirt.vif_driver option from Nova in Juno so we should remove the
variable from devstack since it's useless / confusing.

Change-Id: I70a8cb4a3606eb5eabd3c0ef331945e72c80543a
diff --git a/lib/neutron-legacy b/lib/neutron-legacy
index da8c064..f381f6e 100644
--- a/lib/neutron-legacy
+++ b/lib/neutron-legacy
@@ -158,8 +158,6 @@
 Q_USE_DEBUG_COMMAND=${Q_USE_DEBUG_COMMAND:-False}
 # The name of the default q-l3 router
 Q_ROUTER_NAME=${Q_ROUTER_NAME:-router1}
-# nova vif driver that all plugins should use
-NOVA_VIF_DRIVER=${NOVA_VIF_DRIVER:-"nova.virt.libvirt.vif.LibvirtGenericVIFDriver"}
 Q_NOTIFY_NOVA_PORT_STATUS_CHANGES=${Q_NOTIFY_NOVA_PORT_STATUS_CHANGES:-True}
 Q_NOTIFY_NOVA_PORT_DATA_CHANGES=${Q_NOTIFY_NOVA_PORT_DATA_CHANGES:-True}
 VIF_PLUGGING_IS_FATAL=${VIF_PLUGGING_IS_FATAL:-True}
@@ -485,10 +483,9 @@
         iniset $NOVA_CONF DEFAULT security_group_api neutron
     fi
 
-    # set NOVA_VIF_DRIVER and optionally set options in nova_conf
+    # optionally set options in nova_conf
     neutron_plugin_create_nova_conf
 
-    iniset $NOVA_CONF libvirt vif_driver "$NOVA_VIF_DRIVER"
     iniset $NOVA_CONF DEFAULT linuxnet_interface_driver "$LINUXNET_VIF_DRIVER"
     if is_service_enabled q-meta; then
         iniset $NOVA_CONF neutron service_metadata_proxy "True"
diff --git a/lib/neutron_plugins/README.md b/lib/neutron_plugins/README.md
index 4b220d3..f03000e 100644
--- a/lib/neutron_plugins/README.md
+++ b/lib/neutron_plugins/README.md
@@ -16,9 +16,7 @@
 ``lib/neutron-legacy`` calls the following functions when the ``$Q_PLUGIN`` is enabled
 
 * ``neutron_plugin_create_nova_conf`` :
-  set ``NOVA_VIF_DRIVER`` and optionally set options in nova_conf
-  e.g.
-  NOVA_VIF_DRIVER=${NOVA_VIF_DRIVER:-"nova.virt.libvirt.vif.LibvirtGenericVIFDriver"}
+  optionally set options in nova_conf
 * ``neutron_plugin_install_agent_packages`` :
   install packages that is specific to plugin agent
   e.g.
diff --git a/lib/neutron_plugins/brocade b/lib/neutron_plugins/brocade
index b8166d9..557b94d 100644
--- a/lib/neutron_plugins/brocade
+++ b/lib/neutron_plugins/brocade
@@ -12,7 +12,7 @@
 }
 
 function neutron_plugin_create_nova_conf {
-    NOVA_VIF_DRIVER=${NOVA_VIF_DRIVER:-"nova.virt.libvirt.vif.LibvirtGenericVIFDriver"}
+    :
 }
 
 function neutron_plugin_install_agent_packages {
diff --git a/lib/neutron_plugins/ibm b/lib/neutron_plugins/ibm
index 3660a9f..dd5cfa6 100644
--- a/lib/neutron_plugins/ibm
+++ b/lib/neutron_plugins/ibm
@@ -42,7 +42,6 @@
 }
 
 function neutron_plugin_create_nova_conf {
-    NOVA_VIF_DRIVER=${NOVA_VIF_DRIVER:-"nova.virt.libvirt.vif.LibvirtGenericVIFDriver"}
     # if n-cpu is enabled, then setup integration bridge
     if is_service_enabled n-cpu; then
         neutron_setup_integration_bridge
diff --git a/lib/neutron_plugins/nuage b/lib/neutron_plugins/nuage
index 7bce233..9e5307b 100644
--- a/lib/neutron_plugins/nuage
+++ b/lib/neutron_plugins/nuage
@@ -10,7 +10,6 @@
 function neutron_plugin_create_nova_conf {
     NOVA_OVS_BRIDGE=${NOVA_OVS_BRIDGE:-"br-int"}
     iniset $NOVA_CONF neutron ovs_bridge $NOVA_OVS_BRIDGE
-    NOVA_VIF_DRIVER=${NOVA_VIF_DRIVER:-"nova.virt.libvirt.vif.LibvirtGenericVIFDriver"}
     LIBVIRT_FIREWALL_DRIVER=nova.virt.firewall.NoopFirewallDriver
     iniset $NOVA_CONF DEFAULT firewall_driver $LIBVIRT_FIREWALL_DRIVER
 }
diff --git a/lib/neutron_plugins/oneconvergence b/lib/neutron_plugins/oneconvergence
index 48a368a..0c570e5 100644
--- a/lib/neutron_plugins/oneconvergence
+++ b/lib/neutron_plugins/oneconvergence
@@ -68,7 +68,6 @@
 }
 
 function neutron_plugin_create_nova_conf {
-    NOVA_VIF_DRIVER=${NOVA_VIF_DRIVER:-"nova.virt.libvirt.vif.LibvirtGenericVIFDriver"}
     if ( is_service_enabled n-cpu && ! ( is_service_enabled q-dhcp )) ; then
         setup_integration_bridge
     fi