dt-bindings: arm: amlogic: add bindings for G12B based S922X SoC

Add a specific compatible for the Amlogic G12B family based S922X SoC
to differentiate with the A311D SoC from the same family.
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

@@ -139,6 +139,7 @@ properties:
         items:
           - enum:
               - hardkernel,odroid-n2
+          - const: amlogic,s922x
           - const: amlogic,g12b
 
 ...