staging: comedi: das16m1: remove unnecessary private data comments

These comments are just extra cruft. Removing them also fixes a
checkpatch.pl issue:
WARNING: Block comments use a trailing */ on a separate line

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>