staging: comedi: dt9812: reword comments to fix checkpatch.pl issues

Reword the block comments to fix the checkpatch.pl issues about:

WARNING: Block comments use * on subsequent lines
WARNING: Block comments use a trailing */ on a separate line

For consistency, also reword the previous comments.

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>