Remove unused API function from Nova API
Remove unused API function from Nova API

os-virtual-interfaces is part of nova-network, which Horizon does not support.
No code in Horizon is using this function, and it is no longer necessary.

Change-Id: I118c81db1e581487384677aa0b0020dd35001a29

openstack/horizon,NeCTAR-RC/horizon,noironetworks/horizon,openstack/horizon,noironetworks/horizon,openstack/horizon,noironetworks/horizon,noironetworks/horizon,NeCTAR-RC/horizon,ChameleonCloud/horizon,NeCTAR-RC/horizon,NeCTAR-RC/horizon,ChameleonCloud/horizon,ChameleonCloud/horizon,openstack/horizon,ChameleonCloud/horizon