dt-bindings: rtc: max31335: add max31335 bindings

Document the Analog Devices MAX31335 device tree bindings.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Link: https://lore.kernel.org/r/20231120120114.48657-1-antoniu.miclaus@analog.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>