dt-bindings: arm: amlogic: add bindings for the Amlogic G12B based A311D SoC

Add a specific compatible for the Amlogic G12B bases A311D SoC used
in the Khadas VIM3.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Documentation/devicetree/bindings/arm/amlogic.yaml

@@ -135,6 +135,11 @@ properties:
               - amlogic,u200
           - const: amlogic,g12a
 
+      - description: Boards with the Amlogic Meson G12B A311D SoC
+        items:
+          - const: amlogic,a311d
+          - const: amlogic,g12b
+
       - description: Boards with the Amlogic Meson G12B S922X SoC
         items:
           - enum: