corrected the help string in coho.driver
corrected the help string in coho.driver

fix a typo,Coha should be Coho

Change-Id: Ifd6fa09c973a23603ab6b7a02264156ad58cd42d

j-griffith/cinder,j-griffith/cinder,Datera/cinder,Hybrid-Cloud/cinder,Hybrid-Cloud/cinder,mahak/cinder,ge0rgi/cinder,cloudbase/cinder,eharney/cinder,mahak/cinder,openstack/cinder,openstack/cinder,eharney/cinder,phenoxim/cinder,Datera/cinder,NetApp/cinder,Nexenta/cinder,phenoxim/cinder,cloudbase/cinder,Nexenta/cinder,NetApp/cinder