x86/platform/geode: switch GPIO buttons and LEDs to software properties

Convert GPIO-connected buttons and LEDs in Geode boards to software
nodes/properties, so that support for platform data can be removed from
gpio-keys driver (which will rely purely on generic device properties
for configuration).

To avoid repeating the same data structures over and over and over
factor them out into a new geode-common.c file.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/ZsV6MNS_tUPPSffJ@google.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>