tests: Use enum rather than #defines for tests

tests: Use enum rather than #defines for tests

Change the command test so that it uses an enum, rather than #defines
for offsets into the parms array. This is mainly a cosmetic change, but
brings the test suite into line with the way that we're doing stuff in
the "real" code.

Change-Id: Ia9d72e13230edd4fe13af52ba6816cf775693c36
Reviewed-on: http://gerrit.openafs.org/7133
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Tom Keiser <tkeiser@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementix.org>