iio: prox: srf08: 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: 78f83902 ("iio: distance: srf08: add IIO driver for us ranger")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Andreas Klinger <ak@it-klinger.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-13-jic23@kernel.org

drivers/iio/proximity/srf08.c

@@ -63,11 +63,11 @@ struct srf08_data {
 	int			range_mm;
 	struct mutex		lock;
 
-	/*
-	 * triggered buffer
-	 * 1x16-bit channel + 3x16 padding + 4x16 timestamp
-	 */
-	s16			buffer[8];
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		s16 chan;
+		s64 timestamp __aligned(8);
+	} scan;
 
 	/* Sensor-Type */
 	enum srf08_sensor_type	sensor_type;
@@ -190,9 +190,9 @@ static irqreturn_t srf08_trigger_handler(int irq, void *p)
 
 	mutex_lock(&data->lock);
 
-	data->buffer[0] = sensor_data;
+	data->scan.chan = sensor_data;
 	iio_push_to_buffers_with_timestamp(indio_dev,
-						data->buffer, pf->timestamp);
+					   &data->scan, pf->timestamp);
 
 	mutex_unlock(&data->lock);
 err: