cleanup nova deprecated vif driver code

[Yaguang Tang]

we have generate vif driver which reports vif_type that can replace those specific drivers. the code is depcated in Hvanana and can be safely removed in Icehouse.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/49660

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/49660
Committed: http://github.com/openstack/nova/commit/886ba0856b1dc2baede5e1ee65cf7488320bfe71
Submitter: Jenkins
Branch: master

commit 886ba0856b1dc2baede5e1ee65cf7488320bfe71
Author: Yaguang Tang <email address hidden>
Date: Fri Oct 4 09:13:44 2013 +0800

    Remove deprecated libvirt VIF driver code

    Libvirt vif specific driver classes have been replaced by a generic
    driver LibvirtGenericVIFDriver and are deprecated in Havana, so we
    can remove them safely.

    DocImpact

    Change-Id: Icecb3c9aa4282c511364107d87f8aba517a5ae14
    Closes-Bug: 1235036