platform/x86: x86-android-tablets: Add support for extra buttons on Cyberbook T116

The Cyberbook T116 rugged tablet comes in both Windows and Android versions
and even on the Android version the DSDT is mostly sane. This tablet has
2 extra general purpose buttons in the row with the power + volume-buttons,
labeled P and F.

Use the x86-android-tablets infra to create a gpio-button device for these
2 extra buttons.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230505205901.42649-2-hdegoede@redhat.com