Windows: fix fs setcrypt help message

Windows: fix fs setcrypt help message

Options are on, auth, and off.

Reviewed-on: http://gerrit.openafs.org/6599
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
(cherry picked from commit 898930fc3ca81a5e5dde31967c00cdf5f4734ffa)

Change-Id: I6ef9294554eeedc9f6963a92b815e118fff87139
Reviewed-on: http://gerrit.openafs.org/6825
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>