rtc: rv3029: remove race condition when update STATUS

There is no lock preventing concurrent access to the status register from
bth the rtc subsystem and the hwmon subsystem. Use regmap_update_bits to
ensure updating RV3029_STATUS is properly locked.

Link: https://lore.kernel.org/r/20191214221022.622482-5-alexandre.belloni@bootlin.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>