rtc: rv3028: Add support for "aux-voltage-chargeable" property

rtc: rv3028: Add support for "aux-voltage-chargeable" property

Property "trickle-resistor-ohms" allows us to set trickle charger
resistor. However there is no possibility to disable it afterwards.

Add support for "aux-voltage-chargeable" property which can be used to
enable/disable the trickle charger circuit explicitly. The default
behavior of the code is kept as it is!

Additionally, lets make sure we only update internal EEPROM in case of a
change. This prevents wear due to excessive EEPROM writes on each probe.

Signed-off-by: Andrej Picej <andrej.picej@norik.com>
Link: https://lore.kernel.org/r/20230623081533.76334-1-andrej.picej@norik.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>