san driver: don't use relative Python import
san driver: don't use relative Python import

Replace relative import with absolute import. Relative imports don't
work on Python 3 anymore.

Blueprint cinder-python3
Change-Id: Ie27ee7d8734c59d0739b8e1a2ecc369801d56cf7

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