staging:iio:ad7192: Fix setting ACX

Write to the correct register when setting the ACX bit.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/ad7192.c

@@ -754,7 +754,7 @@ static ssize_t ad7192_set(struct device *dev,
 		else
 			st->mode &= ~AD7192_MODE_ACX;
 
-		ad7192_write_reg(st, AD7192_REG_GPOCON, 3, st->mode);
+		ad7192_write_reg(st, AD7192_REG_MODE, 3, st->mode);
 		break;
 	default:
 		ret = -EINVAL;