iio: proximity: irsd200: Use a struct for scan and iio_push_to_buffers_with_ts()

The driver previously used an array of two s64, then type cast the
pointer to write an s16 to the start. The code is made more readable
using a structure.  At the same time switch to the new
iio_push_to_buffers_with_ts() helper to enable runtime checking of the
size of the source buffer.

Note that this approach uses a structure with holes, so use memset()
to ensure those do not contain old kernel data as this data is passed
to userspace.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250413103443.2420727-17-jic23@kernel.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>