iio: light: vcnl4000: Fix buffer alignment in iio_push_to_buffers_with_timestamp()

Add __aligned(8) to ensure the buffer passed to
iio_push_to_buffers_with_timestamp() is suitable for the naturally
aligned timestamp that will be inserted.

Here an explicit structure is not used, because the holes would
necessitate the addition of an explict memset(), to avoid a kernel
data leak, making for a less minimal fix.

Found during an audit of all callers of iio_push_to_buffers_with_timestamp()

Fixes: 8fe78d52 ("iio: vcnl4000: Add buffer support for VCNL4010/20.")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Mathieu Othacehe <m.othacehe@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210613152301.571002-7-jic23@kernel.org

drivers/iio/light/vcnl4000.c

@@ -908,7 +908,7 @@ static irqreturn_t vcnl4010_trigger_handler(int irq, void *p)
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct vcnl4000_data *data = iio_priv(indio_dev);
 	const unsigned long *active_scan_mask = indio_dev->active_scan_mask;
-	u16 buffer[8] = {0}; /* 1x16-bit + ts */
+	u16 buffer[8] __aligned(8) = {0}; /* 1x16-bit + naturally aligned ts */
 	bool data_read = false;
 	unsigned long isr;
 	int val = 0;