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

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 <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20251126131619.136605-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>