dt-bindings: Add binding for Hardkernel Odroid Go Advance

Add a compatible for the Odroid Go Advance from Hardkernel.
The compatible used by the vendor already is odroid-go2, to distinguish
it from the previous (microcontroller-based) Odroid Go, so we're keeping
that, also to not cause unnecessary incompatibilites.
Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200414082938.2977572-2-heiko@sntech.deSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -358,6 +358,11 @@ properties:
           - const: haoyu,marsboard-rk3066
           - const: rockchip,rk3066a
 
+      - description: Hardkernel Odroid Go Advance
+        items:
+          - const: hardkernel,rk3326-odroid-go2
+          - const: rockchip,rk3326
+
       - description: Hugsun X99 TV Box
         items:
           - const: hugsun,x99