Updated openstack/openstack
Project: openstack/neutron  99b30941b201806186377a2aca8198c1f9488a09
null
Remove confusing comment and code for LBaaS

The comment "the driver is optional" is inconsistent with what actually
done. And "vif_driver = None" after raising an exception makes no sense.
So this patch removes these lines.

Change-Id: I7f3d5b6df61037307e952a478f47c59485601847