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

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: 8fe78d5261e7 ("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