rtc: ds1307: consider aux-voltage-chargeable

Prefer aux-voltage-chargeable over trickle-diode-disable and set diode
accordingly. This is then passed to the chip's appropriate charge setup
function.

Signed-off-by: Bastian Krause <bst@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200917183246.19446-8-bst@pengutronix.de