There are no in-tree users of platform data and any new ones should
either use device tree or static device properties, so let's remove
platform data support.

Tested-by: Andreas Kemnade <andreas@kemnade.info> # Tolino Shine2HD
Link: https://lore.kernel.org/r/20240824055047.1706392-4-dmitry.torokhov@gmail.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>