Fix variable name
Fix variable name

The test was using the wrong variable for the TokenClient (token),
it has been merged since the patch who enables the feature was still
under review in DevStack. This patch fixes the issue by using the
correct variable name (non_admin_token).

Change-Id: Id97ca26f93b742cc3d8d49e98afc581f22360504

cisco-openstack/tempest,masayukig/tempest,vedujoshi/tempest,cisco-openstack/tempest,openstack/tempest,vedujoshi/tempest,openstack/tempest,masayukig/tempest,Juniper/tempest,Juniper/tempest