dt-bindings: memory: renesas,rzg3e-xspi: Document RZ/V2H(P) and RZ/V2N support

dt-bindings: memory: renesas,rzg3e-xspi: Document RZ/V2H(P) and RZ/V2N support

Document support for the Expanded Serial Peripheral Interface (xSPI)
controller found on the Renesas RZ/V2H(P) (R9A09G057) and RZ/V2N
(R9A09G056) SoCs.

The xSPI hardware block on these SoCs is functionally identical to the
one on the RZ/G3E (R9A09G047) SoC. Therefore, the existing driver can be
reused without modification by using `renesas,r9a09g047-xspi` as a
fallback compatible.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250624171605.469724-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>