iio: gyro: bmg160: Fix buffer alignment in iio_push_to_buffers_with_timestamp()

To make code more readable, use a structure to express the channel
layout and ensure the timestamp is 8 byte aligned.

Found during an audit of all calls of uses of
iio_push_to_buffers_with_timestamp()

Fixes: 13426454b6 ("iio: bmg160: Separate i2c and core driver")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-11-jic23@kernel.org

drivers/iio/gyro/bmg160_core.c

@@ -98,7 +98,11 @@ struct bmg160_data {
 	struct iio_trigger *motion_trig;
 	struct iio_mount_matrix orientation;
 	struct mutex mutex;
-	s16 buffer[8];
+	/* Ensure naturally aligned timestamp */
+	struct {
+		s16 chans[3];
+		s64 timestamp __aligned(8);
+	} scan;
 	u32 dps_range;
 	int ev_enable_state;
 	int slope_thres;
@@ -882,12 +886,12 @@ static irqreturn_t bmg160_trigger_handler(int irq, void *p)
 
 	mutex_lock(&data->mutex);
 	ret = regmap_bulk_read(data->regmap, BMG160_REG_XOUT_L,
-			       data->buffer, AXIS_MAX * 2);
+			       data->scan.chans, AXIS_MAX * 2);
 	mutex_unlock(&data->mutex);
 	if (ret < 0)
 		goto err;
 
-	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 					   pf->timestamp);
 err:
 	iio_trigger_notify_done(indio_dev->trig);