dt-bindings: arm: Convert RDA Micro board/soc bindings to json-schema

Convert RDA Micro SoC bindings to DT schema format using json-schema.

Cc: "Andreas Färber" <afaerber@suse.de>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>