dt-bindings: gpu: mali-bifrost: Add compatible for RZ/V2N SoC

Add a compatible string for the Renesas RZ/V2N SoC variants that include a
Mali-G31 GPU. These variants share the same restrictions on interrupts,
clocks, and power domains as the RZ/G2L SoC, so extend the existing schema
validation accordingly.

Signed-off-by: Lad Prabhakar <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring (Arm) <[e-mail]>

Documentation/devicetree/bindings/gpu/arm,mali-bifrost.yaml

···
               - realtek,rtd1619-mali
               - renesas,r9a07g044-mali
               - renesas,r9a07g054-mali
+              - renesas,r9a09g056-mali
               - renesas,r9a09g057-mali
               - rockchip,px30-mali
               - rockchip,rk3562-mali
···
             enum:
               - renesas,r9a07g044-mali
               - renesas,r9a07g054-mali
+              - renesas,r9a09g056-mali
               - renesas,r9a09g057-mali
     then:
       properties: