ptserver: Always set up Ubik security

ptserver: Always set up Ubik security

ptserver was checking for the existence of a suitable KeyFile before
setting up Ubik's security classes. This is uneccessary, because the
behaviour of the afsconf_* functions when a KeyFile doesn't exist
is the same as Ubik's default mechanisms.

So, simplify (and future proof) the code by removing the KeyFile check.

Change-Id: I03df04e99ca4c043c15fc5f5701f8438912a7633
Reviewed-on: http://gerrit.openafs.org/4099
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>