It doesn't make sense to set the RTC to a default value at probe time. Let
the core handle invalid date and time.

Also, this is basically dead code since commit 22652ba7 ("rtc: stop
validating rtc_time in .read_time")
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20210202112934.3612726-1-alexandre.belloni@bootlin.com