Fix IVS vif to correctly delete interfaces on unplug

The IVS unplug method was incorrectly calling the OVS
specific interface removal methods. This corrects it
to call the IVS removal methods.

Fixes: bug #1214532
Change-Id: Ie718e167d5bdcfae0d915ef85976aeeb3449ad18
Merge "Fix IVS vif to correctly delete interfaces on unplug"