libvirt: fix direct OVS plugging
libvirt: fix direct OVS plugging

The commit cd1766287862162aadf1c111a4807f7618f34578 introduced a error
when doing direct OVS plugging.

Closes-bug: #1497896

Change-Id: I6f0ac3085d2dc4345dddd4647fccb540941669e5

fnordahl/nova,rajalokan/nova,cloudbase/nova,edulramirez/nova,vmturbo/nova,zhimin711/nova,hanlind/nova,Juniper/nova,phenoxim/nova,jianghuaw/nova,NeCTAR-RC/nova,vmturbo/nova,mikalstill/nova,jianghuaw/nova,klmitch/nova,cernops/nova,bigswitch/nova,jianghuaw/nova,noironetworks/nova,devendermishrajio/nova,openstack/nova,Juniper/nova,rahulunair/nova,hanlind/nova,rajalokan/nova,sebrandon1/nova,JianyuWang/nova,mikalstill/nova,klmitch/nova,raildo/nova,klmitch/nova,mahak/nova,mikalstill/nova,dims/nova,apporc/nova,klmitch/nova,gooddata/openstack-nova,CCI-MOC/nova,BeyondTheClouds/nova,hanlind/nova,openstack/nova,JianyuWang/nova,MountainWei/nova,noironetworks/nova,dims/nova,sebrandon1/nova,cyx1231st/nova,alaski/nova,vmturbo/nova,mahak/nova,rajalokan/nova,cernops/nova,cloudbase/nova,zhimin711/nova,edulramirez/nova,gooddata/openstack-nova,gooddata/openstack-nova,MountainWei/nova,BeyondTheClouds/nova,sebrandon1/nova,CEG-FYP-OpenStack/scheduler,devendermishrajio/nova,apporc/nova,Juniper/nova,cyx1231st/nova,TwinkleChawla/nova,phenoxim/nova,fnordahl/nova,rajalokan/nova,Francis-Liu/animated-broccoli,BeyondTheClouds/nova,Francis-Liu/animated-broccoli,CEG-FYP-OpenStack/scheduler,NeCTAR-RC/nova,bigswitch/nova,vmturbo/nova,cloudbase/nova,rahulunair/nova,Juniper/nova,openstack/nova,raildo/nova,gooddata/openstack-nova,alaski/nova,jianghuaw/nova,CCI-MOC/nova,cernops/nova,mahak/nova,rahulunair/nova,TwinkleChawla/nova