Remove unused _instance_update() method in compute api
Remove unused _instance_update() method in compute api

The _instance_update() method was previously used in lock/unlock
but that changed when they were converted to use instance objects.

Change-Id: I1f1e00b31792fd13a5b72a15c0cb11cfde75f794

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