Add documentation describing the Nuvoton ma35d1 rtc controller.
Signed-off-by: Jacky Huang <ychuang3@nuvoton.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230925070251.28-2-ychuang570808@gmail.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>