dt-bindings: memory: renesas,rpc-if: Document RZ/G2UL SoC

Document RZ/G2UL RPC-IF bindings. RZ/G2UL RPC-IF is identical to one found
on the RZ/G2L SoC. No driver changes are required as generic compatible
string "renesas,rzg2l-rpc-if" will be used as a fallback.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220501082508.25511-1-biju.das.jz@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>