The fwaas_v2 driver string is specified incorrectly in the fwaas_v2
scenario documentation. Fix it. This was uncovered because it had to
be fixed elsewhere, like puppet-openstack-integration [1].
[1] https://review.openstack.org/635095
Change-Id: Ib68faa4db08f4315c6a2fe137fa8eef199b0255d