staging:iio:ad7887: Use passed in chan spec in ad7887_read_raw

Use the passed in chan spec in ad7887_read_raw instead of alawys using the first
chan spec entry from the chip info data. Since all channels have the same shift
and realbits from a functional point of view it does not matter which chan spec
is used, but the patch makes the a bit more clear.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/ad7887.c

@@ -177,8 +177,8 @@ static int ad7887_read_raw(struct iio_dev *indio_dev,
 
 		if (ret < 0)
 			return ret;
-		*val = (ret >> st->chip_info->channel[0].scan_type.shift) &
-			RES_MASK(st->chip_info->channel[0].scan_type.realbits);
+		*val = ret >> chan->scan_type.shift;
+		*val &= RES_MASK(chan->scan_type.realbits);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		if (st->reg) {
@@ -190,7 +190,7 @@ static int ad7887_read_raw(struct iio_dev *indio_dev,
 			*val = st->chip_info->int_vref_mv;
 		}
 
-		*val2 = st->chip_info->channel[0].scan_type.realbits;
+		*val2 = chan->scan_type.realbits;
 
 		return IIO_VAL_FRACTIONAL_LOG2;
 	}