dt-bindings: i2c: renesas,riic: Document RZ/V2N (R9A09G056) support

Document support for the I2C Bus Interface (RIIC) found on the Renesas
RZ/V2N (R9A09G056) SoC. The RIIC IP is identical to that on RZ/V2H(P),
so `renesas,riic-r9a09g057` will be used as a fallback compatible,
enabling reuse of the existing driver without changes.

Signed-off-by: Lad Prabhakar <[e-mail]>
Reviewed-by: Wolfram Sang <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Andi Shyti <[e-mail]>

Documentation/devicetree/bindings/i2c/renesas,riic.yaml

···
           - enum:
               - renesas,riic-r9a08g045   # RZ/G3S
               - renesas,riic-r9a09g047   # RZ/G3E
+              - renesas,riic-r9a09g056   # RZ/V2N
           - const: renesas,riic-r9a09g057   # RZ/V2H(P)
 
       - const: renesas,riic-r9a09g057   # RZ/V2H(P)