Changes to NVP plugin configuration file

Tweak devstack support to the nicira plugin in order to
reflect changes made in:

https://review.openstack.org/#/c/26427

This complements fixes for bug #1121605

Change-Id: I221466fb40412ceb457d3e888767291a76176aa6
Merge "Changes to NVP plugin configuration file"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp