iio: adc: ad7768-1: Fix too small buffer passed to iio_push_to_buffers_with_timestamp()

Add space for the timestamp to be inserted.  Also ensure correct
alignment for passing to iio_push_to_buffers_with_timestamp()

Fixes: a5f8c7da ("iio: adc: Add AD7768-1 ADC basic support")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501165314.511954-2-jic23@kernel.org
Cc: <Stable@vger.kernel.org>

drivers/iio/adc/ad7768-1.c

@@ -167,6 +167,10 @@ struct ad7768_state {
 	 * transfer buffers to live in their own cache lines.
 	 */
 	union {
+		struct {
+			__be32 chan;
+			s64 timestamp;
+		} scan;
 		__be32 d32;
 		u8 d8[2];
 	} data ____cacheline_aligned;
@@ -469,11 +473,11 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
 
 	mutex_lock(&st->lock);
 
-	ret = spi_read(st->spi, &st->data.d32, 3);
+	ret = spi_read(st->spi, &st->data.scan.chan, 3);
 	if (ret < 0)
 		goto err_unlock;
 
-	iio_push_to_buffers_with_timestamp(indio_dev, &st->data.d32,
+	iio_push_to_buffers_with_timestamp(indio_dev, &st->data.scan,
 					   iio_get_time_ns(indio_dev));
 
 	iio_trigger_notify_done(indio_dev->trig);