drivers: rtc: rtc_mc146818: Added RTC driver for Motorola MC146818B

Added RTC driver that supports Motorola MC146818B
Enabled RTC set/get time and alarm, alarm callback
and update callback.

Counter and RTC uses same hardware in case of
Motorola MC146818, so they can't be used at a time.

Updated stand-alone mc146818 counter dts instances
to support rtc and counter with same compatible
string of "motorola,mc146818" on ia32, atom,
apollo_lake, elhart_lake and raptor_lake platforms.

Signed-off-by: Anisetti Avinash Krishna <anisetti.avinash.krishna@intel.com>