platform/x86: x86-android-tablets: Add support for more then 1 gpio_key

Modify the gpio_keys support in x86_android_tablet_init() for
tablets which have more then 1 key/button which needs to be handled
by the gpio_keys driver.

This requires copying over the struct gpio_keys_button from
the x86_gpio_button struct array to a new gpio_keys_button struct array,
as an added benefit this allows marking the per model x86_gpio_button
arrays __initconst so that they all can be freed after module init().

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230505205901.42649-1-hdegoede@redhat.com