Convert existing binding to dtschema to support validation.

This is a direct conversion with no additions.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240326-rtc-yaml-v3-1-caa430ecace7@gmail.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>