dt-bindings: arm: rockchip: add Zkmagic A95X Z2 description

Add Zkmagic A95X Z2 description for a board with rk3318 processor.
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200808160618.15445-3-jbx6244@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -559,4 +559,9 @@ properties:
         items:
           - const: tronsmart,orion-r68-meta
           - const: rockchip,rk3368
+
+      - description: Zkmagic A95X Z2
+        items:
+          - const: zkmagic,a95x-z2
+          - const: rockchip,rk3318
 ...