dt-bindings: rtc: Add Epson RX8111

Epson RX8111 is an RTC with timestamp functionality. Add devicetree
bindings requiring the compatible string and I2C slave address (reg)
through `trivial-rtc.yaml`.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Link: https://lore.kernel.org/r/4823f303ec8308762430f4f3aaa462be20baef54.1700491765.git.waqar.hameed@axis.com


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