staging: comedi: dt2811: tidy up Digital Input/Output register defines

The digital input and outputs are separate ports even though they share the
same register offset. For aesthetics, define then separately and remove the
redundant information in the comment.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/dt2811.c

@@ -73,6 +73,9 @@
 #define DT2811_DADATA_LO_REG(x)		(0x02 + ((x) * 2)) /* w D/A Data low */
 #define DT2811_DADATA_HI_REG(x)		(0x03 + ((x) * 2)) /* w D/A Data high */
 
+#define DT2811_DI_REG			0x06	/* r   Digital Input Port 0 */
+#define DT2811_DO_REG			0x06	/* w   Digital Output Port 1 */
+
 static const struct comedi_lrange range_dt2811_pgh_ai_5_unipolar = {
 	4, {
 		UNI_RANGE(5),
@@ -128,9 +131,6 @@ static const struct comedi_lrange range_dt2811_pgl_ai_5_bipolar = {
 };
 
 /*
-   0x06 (R) DIO0 Digital Input Port 0
-   (W) DIO1 Digital Output Port 1
-
    0x07 TMRCTR (R/W) Timer/Counter Register
    bits 6,7 - reserved
    bits 5-3 - Timer frequency control (mantissa)
@@ -158,7 +158,6 @@ static const struct comedi_lrange range_dt2811_pgl_ai_5_bipolar = {
 
 #define TIMEOUT 10000
 
-#define DT2811_DIO 6
 #define DT2811_TMRCTR 7
 
 struct dt2811_board {
@@ -254,7 +253,7 @@ static int dt2811_di_insn_bits(struct comedi_device *dev,
 			       struct comedi_subdevice *s,
 			       struct comedi_insn *insn, unsigned int *data)
 {
-	data[1] = inb(dev->iobase + DT2811_DIO);
+	data[1] = inb(dev->iobase + DT2811_DI_REG);
 
 	return insn->n;
 }
@@ -265,7 +264,7 @@ static int dt2811_do_insn_bits(struct comedi_device *dev,
 			       unsigned int *data)
 {
 	if (comedi_dio_update_state(s, data))
-		outb(s->state, dev->iobase + DT2811_DIO);
+		outb(s->state, dev->iobase + DT2811_DO_REG);
 
 	data[1] = s->state;