libafs: Initialize _settok_tokenCell primary flag

libafs: Initialize _settok_tokenCell primary flag

Always set the *primary flag to something in _settok_tokenCell.
Otherwise, the lag may be unset, as it is not required to be
initialized by all callers.

Change-Id: I78c775f8cd70f74f6a344094a6a677cbc74f3281
Reviewed-on: http://gerrit.openafs.org/4521
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>