Add devicetree binding schema for the media I/O block implemented on
Socionext Uniphier SoCs. This block is implemented on LD4, sLD8, Pro4,
and LD11 SoCs.

Media I/O block implemented on Socionext UniPhier SoCs is an integrated
component of the stream type peripherals including SD, USB2.0, eMMC,
and MIO-DMAC.

Media I/O block has a common logic to control the component.
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221213082449.2721-14-hayashi.kunihiko@socionext.comSigned-off-by: Rob Herring <robh@kernel.org>