afs: remove bogus comment from afs_IsTokenExpired

afs: remove bogus comment from afs_IsTokenExpired

Remove an incorrect comment, introduced with commit
adf2e6e827c6caf55247c5e63b88775393156ae5 'Unix CM: Generalise token
storage'.

No functional change is incurred by this commit.

Reviewed-on: https://gerrit.openafs.org/13640
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 54c34d32e884a5bfb2352e7c8767d743ef3e4647)

Change-Id: I00f91947f9cd64694b2021e484b33dc9074fee94
Reviewed-on: https://gerrit.openafs.org/13651
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>