staging: comedi: dt282x: remove unused chan_to_DAC() macro

This macro is not used in the driver. Remove it.
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>

drivers/staging/comedi/drivers/dt282x.c

@@ -345,11 +345,6 @@ struct dt282x_private {
 	int dma_dir;
 };
 
-/*
- *    Some useless abstractions
- */
-#define chan_to_DAC(a)	((a)&1)
-
 static int prep_ai_dma(struct comedi_device *dev, int dma_index, int n)
 {
 	struct dt282x_private *devpriv = dev->private;