staging: comedi: dt282x: remove old unused code

There are two #if 0 blocks that have no recent history of any change.
Remove those code blocks for improved readability of the code.

Signed-off-by: Deepak R Varma <mh12gx2825@gmail.com>
Link: https://lore.kernel.org/r/20200310212545.GA8914@deeUbuntu


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>