nn10300 has a dependency on mc146818_get_time/mc146818_set_time,
which we want to move from the mc146818rtc.h header into the
rtc subsystem, which in turn is not usable on mn10300.
This changes mn10300 to use the modern rtc-cmos driver instead
of the old RTC driver, and that in turn lets us completely
remove the read_persistent_clock/update_persistent_clock callbacks.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
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