Add devicetree binding schema for the peripheral block implemented on
Socionext Uniphier SoCs.

Peripheral block implemented on Socionext UniPhier SoCs is an integrated
component of the peripherals including UART, I2C/FI2C, and SCSSI.

Peripheral block has some function logics 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/20221213082449.2721-13-hayashi.kunihiko@socionext.comSigned-off-by: Rob Herring <robh@kernel.org>