dt-bindings: soc: socionext: Add UniPhier peripheral block

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.com


Signed-off-by: Rob Herring <robh@kernel.org>