Remove instance_type db lookup in prep_resize.
Remove instance_type db lookup in prep_resize.

Remove a db read in prep_resize() by grabbing the instance_type data out
of the instance dict.  The code was unnecessarily looking it up from the
db.

Part of blueprint no-db-compute.

Change-Id: I6e26a8a90f7cfca12426fad2430a0eb73991f42f

bclau/nova,CEG-FYP-OpenStack/scheduler,sebrandon1/nova,LoHChina/nova,imsplitbit/nova,yosshy/nova,eharney/nova,klmitch/nova,badock/nova,petrutlucian94/nova,yatinkumbhare/openstack-nova,vmturbo/nova,gooddata/openstack-nova,tanglei528/nova,noironetworks/nova,orbitfp7/nova,jianghuaw/nova,mikalstill/nova,leilihh/novaha,cloudbase/nova,noironetworks/nova,dims/nova,akash1808/nova,whitepages/nova,jianghuaw/nova,double12gzh/nova,saleemjaveds/https-github.com-openstack-nova,eharney/nova,ted-gould/nova,devendermishrajio/nova_test_latest,bclau/nova,zzicewind/nova,openstack/nova,projectcalico/calico-nova,thomasem/nova,angdraug/nova,BeyondTheClouds/nova,virtualopensystems/nova,sridevikoushik31/nova,maheshp/novatest,Brocade-OpenSource/OpenStack-DNRM-Nova,iuliat/nova,klmitch/nova,DirectXMan12/nova-hacking,imsplitbit/nova,raildo/nova,mmnelemane/nova,JianyuWang/nova,iuliat/nova,dims/nova,sridevikoushik31/openstack,TwinkleChawla/nova,alvarolopez/nova,mgagne/nova,gooddata/openstack-nova,tangfeixiong/nova,JioCloud/nova,fajoy/nova,zhimin711/nova,CloudServer/nova,raildo/nova,vmturbo/nova,NeCTAR-RC/nova,apporc/nova,affo/nova,tianweizhang/nova,shahar-stratoscale/nova,badock/nova,petrutlucian94/nova_dev,rickerc/nova_audit,apporc/nova,BeyondTheClouds/nova,viggates/nova,vmturbo/nova,mandeepdhami/nova,whitepages/nova,projectcalico/calico-nova,DirectXMan12/nova-hacking,akash1808/nova_test_latest,TwinkleChawla/nova,eonpatapon/nova,thomasem/nova,petrutlucian94/nova_dev,rahulunair/nova,blueboxgroup/nova,redhat-openstack/nova,fajoy/nova,aristanetworks/arista-ovs-nova,CCI-MOC/nova,ted-gould/nova,CiscoSystems/nova,shootstar/novatest,NeCTAR-RC/nova,sridevikoushik31/nova,cloudbase/nova-virtualbox,sebrandon1/nova,cyx1231st/nova,hanlind/nova,scripnichenko/nova,leilihh/novaha,devendermishrajio/nova_test_latest,vladikr/nova_drafts,Brocade-OpenSource/OpenStack-DNRM-Nova,yosshy/nova,edulramirez/nova,petrutlucian94/nova,CEG-FYP-OpenStack/scheduler,barnsnake351/nova,saleemjaveds/https-github.com-openstack-nova,spring-week-topos/nova-week,rajalokan/nova,citrix-openstack-build/nova,sridevikoushik31/openstack,mikalstill/nova,maoy/zknova,watonyweng/nova,openstack/nova,devendermishrajio/nova,gspilio/nova,Juniper/nova,kimjaejoong/nova,joker946/nova,OpenAcademy-OpenStack/nova-scheduler,alaski/nova,Tehsmash/nova,Yusuke1987/openstack_template,tianweizhang/nova,maoy/zknova,luogangyi/bcec-nova,mikalstill/nova,Juniper/nova,Yusuke1987/openstack_template,devendermishrajio/nova,MountainWei/nova,cyx1231st/nova,tealover/nova,orbitfp7/nova,nikesh-mahalka/nova,vladikr/nova_drafts,barnsnake351/nova,devoid/nova,dawnpower/nova,mandeepdhami/nova,OpenAcademy-OpenStack/nova-scheduler,Triv90/Nova,varunarya10/nova_test_latest,Stavitsky/nova,bigswitch/nova,openstack/nova,belmiromoreira/nova,blueboxgroup/nova,affo/nova,gspilio/nova,berrange/nova,JioCloud/nova,mmnelemane/nova,ntt-sic/nova,DirectXMan12/nova-hacking,viggates/nova,felixma/nova,varunarya10/nova_test_latest,houshengbo/nova_vmware_compute_driver,alexandrucoman/vbox-nova-driver,Metaswitch/calico-nova,houshengbo/nova_vmware_compute_driver,felixma/nova,berrange/nova,TieWei/nova,dstroppa/openstack-smartos-nova-grizzly,klmitch/nova,silenceli/nova,houshengbo/nova_vmware_compute_driver,kimjaejoong/nova,Francis-Liu/animated-broccoli,yrobla/nova,klmitch/nova,mgagne/nova,Yuriy-Leonov/nova,vmturbo/nova,j-carpentier/nova,edulramirez/nova,eayunstack/nova,tangfeixiong/nova,CCI-MOC/nova,LoHChina/nova,shail2810/nova,gooddata/openstack-nova,rajalokan/nova,aristanetworks/arista-ovs-nova,plumgrid/plumgrid-nova,phenoxim/nova,mahak/nova,zaina/nova,BeyondTheClouds/nova,sebrandon1/nova,eonpatapon/nova,maelnor/nova,jianghuaw/nova,rajalokan/nova,double12gzh/nova,hanlind/nova,cernops/nova,zhimin711/nova,plumgrid/plumgrid-nova,Tehsmash/nova,adelina-t/nova,maoy/zknova,sacharya/nova,tudorvio/nova,SUSE-Cloud/nova,eayunstack/nova,maelnor/nova,yatinkumbhare/openstack-nova,nikesh-mahalka/nova,dstroppa/openstack-smartos-nova-grizzly,bigswitch/nova,Stavitsky/nova,takeshineshiro/nova,Juniper/nova,Juniper/nova,virtualopensystems/nova,ntt-sic/nova,bgxavier/nova,watonyweng/nova,mahak/nova,tanglei528/nova,dstroppa/openstack-smartos-nova-grizzly,fajoy/nova,citrix-openstack-build/nova,isyippee/nova,rickerc/nova_audit,zzicewind/nova,belmiromoreira/nova,sridevikoushik31/nova,dawnpower/nova,leilihh/nova,SUSE-Cloud/nova,rahulunair/nova,JianyuWang/nova,rahulunair/nova,aristanetworks/arista-ovs-nova,shootstar/novatest,cloudbase/nova,cernops/nova,jeffrey4l/nova,rrader/nova-docker-plugin,jeffrey4l/nova,alaski/nova,joker946/nova,ruslanloman/nova,sacharya/nova,alvarolopez/nova,fnordahl/nova,alexandrucoman/vbox-nova-driver,tudorvio/nova,maheshp/novatest,cloudbase/nova,shahar-stratoscale/nova,ewindisch/nova,jianghuaw/nova,phenoxim/nova,cloudbau/nova,Metaswitch/calico-nova,sridevikoushik31/nova,akash1808/nova_test_latest,Francis-Liu/animated-broccoli,silenceli/nova,ruslanloman/nova,Triv90/Nova,yrobla/nova,bgxavier/nova,gooddata/openstack-nova,tealover/nova,Triv90/Nova,cloudbau/nova,scripnichenko/nova,CloudServer/nova,leilihh/nova,zaina/nova,JioCloud/nova_test_latest,gspilio/nova,angdraug/nova,cloudbase/nova-virtualbox,mahak/nova,rajalokan/nova,ewindisch/nova,yrobla/nova,MountainWei/nova,Yuriy-Leonov/nova,redhat-openstack/nova,sridevikoushik31/openstack,maheshp/novatest,cernops/nova,fnordahl/nova,spring-week-topos/nova-week,luogangyi/bcec-nova,akash1808/nova,TieWei/nova,qwefi/nova,rrader/nova-docker-plugin,takeshineshiro/nova,CiscoSystems/nova,devoid/nova,isyippee/nova,hanlind/nova,j-carpentier/nova,qwefi/nova,adelina-t/nova,JioCloud/nova_test_latest,shail2810/nova