iio: light: vcnl4035: 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 potential
kernel data leak, making for a less minimal fix.

Fixes: 55707294 ("iio: light: Add support for vishay vcnl4035")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Parthiban Nallathambi <pn@denx.de>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210613152301.571002-8-jic23@kernel.org