Add FSSYNC debug logging

Add FSSYNC debug logging

Add logging for what FSSYNC commands are being received by the
fileserver, so it is possible to see what's going on with FSSYNC. Log at
level 125, since this isn't interesting unless you knows some FSSYNC
details, and it can get quite verbose.

Change-Id: Ia067d3ba5084a919332989aac437ae4d4082e2e4
Reviewed-on: http://gerrit.openafs.org/1349
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Alistair Ferguson <alistair.ferguson@mac.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>