Fix root-diks hint for RHOS < 10
Fix root-diks hint for RHOS < 10

Hint 'name' for defining root disk is invalid for RHOS versions
 before 10. This results in error:
  InstanceDeployFailure:
    RPC do_node_deploy failed to validate deploy or power info.
    Error: The hints "name" are invalid.
      Valid hints are: "model, wwn, vendor, serial, size"

Change-Id: If5d802fb78486fecb2338d9280a516e7b2d921eb

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared