iio: humidity: am2315: 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: 0d96d5ea ("iio: humidity: Add triggered buffer support for AM2315")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-12-jic23@kernel.org

drivers/iio/humidity/am2315.c

@@ -32,7 +32,11 @@
 struct am2315_data {
 	struct i2c_client *client;
 	struct mutex lock;
-	s16 buffer[8]; /* 2x16-bit channels + 2x16 padding + 4x16 timestamp */
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		s16 chans[2];
+		s64 timestamp __aligned(8);
+	} scan;
 };
 
 struct am2315_sensor_data {
@@ -166,20 +170,20 @@ static irqreturn_t am2315_trigger_handler(int irq, void *p)
 
 	mutex_lock(&data->lock);
 	if (*(indio_dev->active_scan_mask) == AM2315_ALL_CHANNEL_MASK) {
-		data->buffer[0] = sensor_data.hum_data;
-		data->buffer[1] = sensor_data.temp_data;
+		data->scan.chans[0] = sensor_data.hum_data;
+		data->scan.chans[1] = sensor_data.temp_data;
 	} else {
 		i = 0;
 		for_each_set_bit(bit, indio_dev->active_scan_mask,
 				 indio_dev->masklength) {
-			data->buffer[i] = (bit ? sensor_data.temp_data :
-						 sensor_data.hum_data);
+			data->scan.chans[i] = (bit ? sensor_data.temp_data :
+					       sensor_data.hum_data);
 			i++;
 		}
 	}
 	mutex_unlock(&data->lock);
 
-	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);