odk: Clean up comments

Change-Id: I38aa34192244cdd29e1cce7ac612aa9cd5f9e8a1
Reviewed-on: https://gerrit.libreoffice.org/11006
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>