staging:iio:hmc5843: Fix measurement conversion

recently broken, cd6fe065
staging:iio:hmc5843: Use i2c_smbus_read_word_swapped()
Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/staging/iio/magnetometer/hmc5843.c

@@ -229,7 +229,7 @@ static int hmc5843_read_measurement(struct iio_dev *indio_dev,
 	if (result < 0)
 		return -EINVAL;
 
-	*val = result;
+	*val = sign_extend32(result, 15);
 	return IIO_VAL_INT;
 }