sunxi: board: Add PinePhone DT selection logic

sunxi: board: Add PinePhone DT selection logic

There are two different publicly-released revisions of the PinePhone
hardware, versions 1.1 and 1.2; and they need different device trees.
Since some GPIO pins were rerouted, we can use that to distinguish
between them.

Acked-by: Maxime Ripard <[email protected]>
Reviewed-by: Andre Przywara <[email protected]>
Signed-off-by: Samuel Holland <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>