dt-bindings: rtc: digicolor-rtc: move to trivial-rtc

dt-bindings: rtc: digicolor-rtc: move to trivial-rtc

Convert existing binding to dtschema to support validation.

This device meets the requirements to be moved to trivial-rtc
(compatible, reg and a single interrupt).

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-v3-3-caa430ecace7@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>