iio: prox: pulsed-light: 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: cb119d53 ("iio: proximity: add support for PulsedLight LIDAR")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Matt Ranostay <matt.ranostay@konsulko.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-14-jic23@kernel.org

drivers/iio/proximity/pulsedlight-lidar-lite-v2.c

@@ -44,7 +44,11 @@ struct lidar_data {
 	int (*xfer)(struct lidar_data *data, u8 reg, u8 *val, int len);
 	int i2c_enabled;
 
-	u16 buffer[8]; /* 2 byte distance + 8 byte timestamp */
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		u16 chan;
+		s64 timestamp __aligned(8);
+	} scan;
 };
 
 static const struct iio_chan_spec lidar_channels[] = {
@@ -230,9 +234,9 @@ static irqreturn_t lidar_trigger_handler(int irq, void *private)
 	struct lidar_data *data = iio_priv(indio_dev);
 	int ret;
 
-	ret = lidar_get_measurement(data, data->buffer);
+	ret = lidar_get_measurement(data, &data->scan.chan);
 	if (!ret) {
-		iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+		iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 						   iio_get_time_ns(indio_dev));
 	} else if (ret != -EINVAL) {
 		dev_err(&data->client->dev, "cannot read LIDAR measurement");