staging: comedi: comedi_compat32.c: reformat other block comments

Use the usual block comment style.  Combine some consecutive comments
into block comments.  Also remove part of a comment referring to
`ptr_to_compat()` not being implemented until kernel version 2.6.11 as
it's irrelevant.

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