ieee802154: at86rf230: drop support for platform data

There are no users of platform data in the mainline tree, and new
boards should use either ACPI or device tree, so let's stop supporting
it. This will help with converting the driver to gpiod API.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20230201053447.4098486-1-dmitry.torokhov@gmail.com


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>