staging: comedi: dt9812: remove some #if 0'ed out code

The struct dt9812_usb_cmd definition contains some #if 0'ed
out code that would cause build errors if enabled. Just remove
it.

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