Specify lld in tgt config backends
Specify lld in tgt config backends

Otherwise when running tgt-admin --delete, it might forget
to invoke tgtadmn with "--lld iscsi" in order to delete the low-level
iscsi exports, which can cause crashes or hangs later on.

Closes-Bug: #1311640
Change-Id: I436c67c30565089236e987d84ac2609eedd2d2c7

mahak/cinder,Paul-Ezell/cinder-1,dims/cinder,Hybrid-Cloud/cinder,github-borat/cinder,eharney/cinder,bswartz/cinder,j-griffith/cinder,j-griffith/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,cloudbase/cinder,dims/cinder,mahak/cinder,Akrog/cinder,phenoxim/cinder,rakeshmi/cinder,petrutlucian94/cinder,nexusriot/cinder,redhat-openstack/cinder,Datera/cinder,abusse/cinder,JioCloud/cinder,alex8866/cinder,petrutlucian94/cinder,manojhirway/ExistingImagesOnNFS,Nexenta/cinder,julianwang/cinder,Thingee/cinder,duhzecca/cinder,takeshineshiro/cinder,leilihh/cinder,openstack/cinder,hguemar/cinder,julianwang/cinder,bswartz/cinder,apporc/cinder,ge0rgi/cinder,Accelerite/cinder,leilihh/cinder,sasukeh/cinder,manojhirway/ExistingImagesOnNFS,saeki-masaki/cinder,tlakshman26/cinder-new-branch,duhzecca/cinder,scottdangelo/RemoveVolumeMangerLocks,sasukeh/cinder,Thingee/cinder,eharney/cinder,scottdangelo/RemoveVolumeMangerLocks,phenoxim/cinder,CloudServer/cinder,Nexenta/cinder,scality/cinder,cloudbase/cinder,JioCloud/cinder,nexusriot/cinder,nikesh-mahalka/cinder,CloudServer/cinder,winndows/cinder,scality/cinder,tlakshman26/cinder-new-branch,takeshineshiro/cinder,winndows/cinder,potsmaster/cinder,Paul-Ezell/cinder-1,Hybrid-Cloud/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,nikesh-mahalka/cinder,tlakshman26/cinder-https-changes,github-borat/cinder,Datera/cinder,hguemar/cinder,saeki-masaki/cinder,Thingee/cinder,Akrog/cinder,potsmaster/cinder,blueboxgroup/cinder,blueboxgroup/cinder,rakeshmi/cinder,abusse/cinder,NetApp/cinder,redhat-openstack/cinder,apporc/cinder,Accelerite/cinder,tlakshman26/cinder-https-changes,NetApp/cinder,alex8866/cinder,openstack/cinder