ptserver: Don't ignore ubik_Write failures

If we can't write to the ubik database, then that's a bad thing.
Don't ignore it.

Caught by clang-analyzer

Reviewed-on: http://gerrit.openafs.org/9176
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 860c34ba938602387f78c10c2f548fb8a523a9cd)

Change-Id: Id379d94844e6cc520829b4ef6015d0a004fdbc42
Reviewed-on: http://gerrit.openafs.org/9526
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>