getInterfaceDriver was ranemed

create_lbaas_manifests tried to use the old getInterfaceDriver function.

It caused the following error:
ERROR : global name 'getInterfaceDriver' is not defined

Switching to the get_if_driver() function.

Change-Id: Id84da4c02e93e424da697e225412c39295495b6c
(cherry picked from commit 8c9a8269d7fe68b6bc20930bd1e1f7c3c89c3213)
Merge "getInterfaceDriver was ranemed" into havana