dt-bindings: mmc: renesas,sdhi: Document RZ/V2M support

Document support for the SD Card/MMC interface on the Renesas
RZ/V2M (a.k.a. r9a09g011) SoC.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20221213230129.549968-3-fabrizio.castro.jz@renesas.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>