iio: imu: inv_mpu6050: fix an error code problem in inv_mpu6050_read_raw

inv_mpu6050_sensor_show() can return -EINVAL or IIO_VAL_INT. Return the
true value rather than only return IIO_VAL_INT.

Fixes: d5098447147c ("iio: imu: mpu6050: add calibration offset support")
Signed-off-by: Su Hui <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/imu/inv_mpu6050/inv_mpu_core.c

···
 			ret = inv_mpu6050_sensor_show(st, st->reg->gyro_offset,
 						chan->channel2, val);
 			mutex_unlock(&st->lock);
-			return IIO_VAL_INT;
+			return ret;
 		case IIO_ACCEL:
 			mutex_lock(&st->lock);
 			ret = inv_mpu6050_sensor_show(st, st->reg->accl_offset,
 						chan->channel2, val);
 			mutex_unlock(&st->lock);
-			return IIO_VAL_INT;
+			return ret;
 
 		default:
 			return -EINVAL;