staging: comedi: dt3000: remove #if 0'ed out code

Replace the disabled code in dt3k_dio_config() with a comment in case
it's actually needed.

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>