rtc: sun6i: Add Allwinner H616 support

The H616 RTC changes its day storage to the newly introduced linear day
scheme, so pair the new compatible string with this feature flag.
The RTC clock parts are handled in a separate driver now, so we skip
the clock parts in this driver completely.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220211122643.1343315-7-andre.przywara@arm.com