dt-bindings: arm: fsl: add NXP S32G3 board

Add bindings for NXP S32G3 Reference Design Board 3 (S32G-VNP-RDB3) [1]

[1]
https://www.nxp.com/design/design-center/designs/s32g3-vehicle-networking-reference-design:S32G-VNP-RDB3

Signed-off-by: Wadim Mueller <wafgo01@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: wafgo

Documentation/devicetree/bindings/arm/fsl.yaml

@@ -1544,6 +1544,12 @@ properties:
               - nxp,s32g274a-rdb2
           - const: nxp,s32g2
 
+      - description: S32G3 based Boards
+        items:
+          - enum:
+              - nxp,s32g399a-rdb3
+          - const: nxp,s32g3
+
       - description: S32V234 based Boards
         items:
           - enum: