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 <mripard@kernel.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>