platform/surface: Move Surface 3 Button driver to platform/surface

Move the Surface 3 Button driver from platform/x86 to the newly created
platform/surface directory.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201009141128.683254-4-luzmaximilian@gmail.com


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