spi: dt-bindings: renesas,rzv2h-rspi: Document RZ/V2N SoC support

Document the RSPI controller on the Renesas RZ/V2N SoC. The block is
compatible with the RSPI implementation found on the RZ/V2H(P) family.

Signed-off-by: Lad Prabhakar <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/spi/renesas,rzv2h-rspi.yaml

···
           - renesas,r9a09g057-rspi # RZ/V2H(P)
           - renesas,r9a09g077-rspi # RZ/T2H
       - items:
+          - const: renesas,r9a09g056-rspi # RZ/V2N
+          - const: renesas,r9a09g057-rspi
+      - items:
           - const: renesas,r9a09g087-rspi # RZ/N2H
           - const: renesas,r9a09g077-rspi # RZ/T2H