Adds support for settings/getting RTC time and using alarm/update feature.
The alarm option needs all fields to be set due to a hardware limitation.
RTC shares the same interrupt with the watchdog. Thus shared
interrupts must be enabled when WDT and RTC both need to trigger the ISR.
Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>
Andriy Gelman