ptserver: fix errant debug message log level

Fix the log level a debugging message introduced
in commit 9ddf9eca56e02be978ff7d065ee16c85de2cfb06.
Thanks to Ben Kaduk for reporting this issue.

Change-Id: I8913472aba8fe5247a29e31e3f04090bc0fce64e
Reviewed-on: http://gerrit.openafs.org/11314
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>