rtc: Add driver for Epson RX8111

Epson RX8111 is an RTC with alarm, timer and timestamp functionality.
Add a basic driver with support for only reading/writing time (for now).

Signed-off-by: Waqar Hameed <waqar.hameed@axis.com>
Link: https://lore.kernel.org/r/0c3e1b03f276da47b26ac50f5d0ddf5c67aabe5c.1700491765.git.waqar.hameed@axis.com


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