dt-bindings: arm: samsung: document SMDK2416 board binding

Add binding for the SMDK2416 board.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/arm/samsung/samsung-boards.yaml

···
     const: '/'
   compatible:
     oneOf:
+      - description: S3C2416 based boards
+        items:
+          - enum:
+              - samsung,smdk2416                # Samsung SMDK2416
+          - const: samsung,s3c2416
+
       - description: S5PV210 based boards
         items:
           - enum: