libvirt : remove broken olso_config choices option
libvirt : remove broken olso_config choices option

Changeset ed9f1b8b restricted the allowed options for iscsi_iface
to the allowed transports mentioned in the help text. iface &
transport are distinct entities for open-iscsi, and an iface is
generally a mix of transport plus an underlying interface, hence
this change was incorrect. This breaks transport support and is
generally incorrect, hence reverting

Closes-Bug:1466730
Change-Id: I687fb9c95133dbbb193004df44794404b58ca692

ted-gould/nova,edulramirez/nova,varunarya10/nova_test_latest,iuliat/nova,felixma/nova,NeCTAR-RC/nova,devendermishrajio/nova,jianghuaw/nova,cloudbase/nova,alaski/nova,j-carpentier/nova,bigswitch/nova,cernops/nova,dims/nova,MountainWei/nova,apporc/nova,JianyuWang/nova,nikesh-mahalka/nova,yosshy/nova,fnordahl/nova,mikalstill/nova,felixma/nova,isyippee/nova,Francis-Liu/animated-broccoli,eonpatapon/nova,NeCTAR-RC/nova,BeyondTheClouds/nova,hanlind/nova,watonyweng/nova,rahulunair/nova,cloudbase/nova,Juniper/nova,JioCloud/nova_test_latest,sebrandon1/nova,TwinkleChawla/nova,JioCloud/nova_test_latest,klmitch/nova,CCI-MOC/nova,vmturbo/nova,raildo/nova,mahak/nova,edulramirez/nova,CEG-FYP-OpenStack/scheduler,Juniper/nova,zaina/nova,klmitch/nova,dims/nova,ruslanloman/nova,zhimin711/nova,rajalokan/nova,rahulunair/nova,jianghuaw/nova,klmitch/nova,ted-gould/nova,jianghuaw/nova,isyippee/nova,fnordahl/nova,watonyweng/nova,mmnelemane/nova,TwinkleChawla/nova,eonpatapon/nova,cernops/nova,devendermishrajio/nova_test_latest,MountainWei/nova,jianghuaw/nova,JianyuWang/nova,noironetworks/nova,whitepages/nova,rajalokan/nova,bigswitch/nova,zaina/nova,rajalokan/nova,openstack/nova,ruslanloman/nova,j-carpentier/nova,BeyondTheClouds/nova,shail2810/nova,devendermishrajio/nova,rajalokan/nova,LoHChina/nova,rahulunair/nova,takeshineshiro/nova,noironetworks/nova,iuliat/nova,scripnichenko/nova,akash1808/nova_test_latest,nikesh-mahalka/nova,gooddata/openstack-nova,barnsnake351/nova,sebrandon1/nova,cernops/nova,mahak/nova,cyx1231st/nova,zzicewind/nova,gooddata/openstack-nova,Juniper/nova,BeyondTheClouds/nova,openstack/nova,takeshineshiro/nova,mikalstill/nova,apporc/nova,Francis-Liu/animated-broccoli,shail2810/nova,LoHChina/nova,devendermishrajio/nova_test_latest,cloudbase/nova,klmitch/nova,openstack/nova,cyx1231st/nova,zhimin711/nova,gooddata/openstack-nova,akash1808/nova_test_latest,scripnichenko/nova,phenoxim/nova,alaski/nova,varunarya10/nova_test_latest,mahak/nova,vmturbo/nova,raildo/nova,mmnelemane/nova,Juniper/nova,zzicewind/nova,mikalstill/nova,phenoxim/nova,CCI-MOC/nova,sebrandon1/nova,barnsnake351/nova,hanlind/nova,vmturbo/nova,gooddata/openstack-nova,yosshy/nova,hanlind/nova,CEG-FYP-OpenStack/scheduler,whitepages/nova,vmturbo/nova