dt-bindings: arm: amlogic: add G12B bindings

Add compatible for the Amlogic G12B SoC, sharing most of the
features and architecture with the G12A SoC.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Documentation/devicetree/bindings/arm/amlogic.yaml

@@ -135,4 +135,8 @@ properties:
               - amlogic,u200
           - const: amlogic,g12a
 
+      - description: Boards with the Amlogic Meson G12B S922X SoC
+        items:
+          - const: amlogic,g12b
+
 ...