Remove useless variable from libvirt/driver.py
Remove useless variable from libvirt/driver.py

There are some variables in libvirt/driver.py were never used, so
we can just remove them.

Change-Id: Ie29bfbeef8c185697aa94a6e05e67a70436302c8

MountainWei/nova,cloudbase/nova,akash1808/nova_test_latest,joker946/nova,ewindisch/nova,fnordahl/nova,zaina/nova,takeshineshiro/nova,alexandrucoman/vbox-nova-driver,jianghuaw/nova,ruslanloman/nova,JioCloud/nova,barnsnake351/nova,raildo/nova,tanglei528/nova,thomasem/nova,redhat-openstack/nova,isyippee/nova,yatinkumbhare/openstack-nova,shail2810/nova,JianyuWang/nova,klmitch/nova,rajalokan/nova,gooddata/openstack-nova,kimjaejoong/nova,BeyondTheClouds/nova,CloudServer/nova,tealover/nova,fnordahl/nova,watonyweng/nova,raildo/nova,openstack/nova,devendermishrajio/nova,Tehsmash/nova,shahar-stratoscale/nova,whitepages/nova,rajalokan/nova,dawnpower/nova,BeyondTheClouds/nova,petrutlucian94/nova,ruslanloman/nova,JioCloud/nova,apporc/nova,MountainWei/nova,tanglei528/nova,cernops/nova,affo/nova,orbitfp7/nova,takeshineshiro/nova,NeCTAR-RC/nova,eharney/nova,Metaswitch/calico-nova,scripnichenko/nova,hanlind/nova,kimjaejoong/nova,phenoxim/nova,cyx1231st/nova,isyippee/nova,hanlind/nova,dims/nova,belmiromoreira/nova,Stavitsky/nova,Tehsmash/nova,CEG-FYP-OpenStack/scheduler,badock/nova,imsplitbit/nova,eharney/nova,blueboxgroup/nova,mahak/nova,openstack/nova,eonpatapon/nova,LoHChina/nova,spring-week-topos/nova-week,vmturbo/nova,vladikr/nova_drafts,double12gzh/nova,apporc/nova,rrader/nova-docker-plugin,Juniper/nova,CCI-MOC/nova,virtualopensystems/nova,alvarolopez/nova,zhimin711/nova,barnsnake351/nova,tudorvio/nova,akash1808/nova_test_latest,sebrandon1/nova,CiscoSystems/nova,sebrandon1/nova,mandeepdhami/nova,gooddata/openstack-nova,imsplitbit/nova,whitepages/nova,affo/nova,devendermishrajio/nova,double12gzh/nova,dawnpower/nova,alvarolopez/nova,edulramirez/nova,akash1808/nova,OpenAcademy-OpenStack/nova-scheduler,CCI-MOC/nova,rajalokan/nova,Metaswitch/calico-nova,j-carpentier/nova,zhimin711/nova,JioCloud/nova_test_latest,bigswitch/nova,CEG-FYP-OpenStack/scheduler,devendermishrajio/nova_test_latest,alexandrucoman/vbox-nova-driver,cloudbase/nova-virtualbox,jianghuaw/nova,OpenAcademy-OpenStack/nova-scheduler,alaski/nova,cernops/nova,cyx1231st/nova,spring-week-topos/nova-week,JianyuWang/nova,jianghuaw/nova,vmturbo/nova,ted-gould/nova,berrange/nova,vmturbo/nova,CloudServer/nova,mahak/nova,sebrandon1/nova,eonpatapon/nova,mikalstill/nova,Francis-Liu/animated-broccoli,klmitch/nova,joker946/nova,tianweizhang/nova,luogangyi/bcec-nova,mikalstill/nova,petrutlucian94/nova_dev,mmnelemane/nova,nikesh-mahalka/nova,mgagne/nova,maelnor/nova,leilihh/novaha,tudorvio/nova,cloudbase/nova-virtualbox,cloudbase/nova,gooddata/openstack-nova,eayunstack/nova,leilihh/nova,varunarya10/nova_test_latest,LoHChina/nova,Juniper/nova,sacharya/nova,rahulunair/nova,phenoxim/nova,felixma/nova,jeffrey4l/nova,varunarya10/nova_test_latest,klmitch/nova,Francis-Liu/animated-broccoli,BeyondTheClouds/nova,orbitfp7/nova,edulramirez/nova,luogangyi/bcec-nova,viggates/nova,yosshy/nova,TwinkleChawla/nova,belmiromoreira/nova,adelina-t/nova,berrange/nova,klmitch/nova,devendermishrajio/nova_test_latest,mahak/nova,mikalstill/nova,openstack/nova,Juniper/nova,angdraug/nova,Yusuke1987/openstack_template,yosshy/nova,maelnor/nova,mgagne/nova,rajalokan/nova,rahulunair/nova,ted-gould/nova,cloudbase/nova,zzicewind/nova,shail2810/nova,badock/nova,hanlind/nova,TwinkleChawla/nova,silenceli/nova,sacharya/nova,tianweizhang/nova,eayunstack/nova,watonyweng/nova,redhat-openstack/nova,thomasem/nova,noironetworks/nova,vladikr/nova_drafts,rrader/nova-docker-plugin,mmnelemane/nova,saleemjaveds/https-github.com-openstack-nova,viggates/nova,projectcalico/calico-nova,vmturbo/nova,tangfeixiong/nova,alaski/nova,ewindisch/nova,silenceli/nova,j-carpentier/nova,yatinkumbhare/openstack-nova,zzicewind/nova,Stavitsky/nova,NeCTAR-RC/nova,devoid/nova,Yusuke1987/openstack_template,noironetworks/nova,petrutlucian94/nova_dev,gooddata/openstack-nova,nikesh-mahalka/nova,shahar-stratoscale/nova,projectcalico/calico-nova,iuliat/nova,virtualopensystems/nova,jeffrey4l/nova,leilihh/novaha,bigswitch/nova,dims/nova,petrutlucian94/nova,tealover/nova,iuliat/nova,adelina-t/nova,blueboxgroup/nova,scripnichenko/nova,mandeepdhami/nova,CiscoSystems/nova,jianghuaw/nova,zaina/nova,rahulunair/nova,saleemjaveds/https-github.com-openstack-nova,tangfeixiong/nova,felixma/nova,JioCloud/nova_test_latest,akash1808/nova,bgxavier/nova,cernops/nova,angdraug/nova,bgxavier/nova,leilihh/nova,Juniper/nova,devoid/nova