dt-bindings: rtc: ds1307: let aux-voltage-chargeable supersede trickle-diode-disable

trickle-diode-disable is deprecated, so reflect that in the driver's
binding and add the new aux-voltage-chargeable.
Signed-off-by: Bastian Krause <bst@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200917183246.19446-3-bst@pengutronix.de

Documentation/devicetree/bindings/rtc/rtc-ds1307.txt

@@ -31,9 +31,16 @@ Optional properties:
 	Selected resistor for trickle charger
 	Possible values are 250, 2000, 4000
 	Should be given if trickle charger should be enabled
-- trickle-diode-disable : ds1339, ds1340 and ds 1388 only
+- aux-voltage-chargeable: ds1339, ds1340 and ds1388 only
+	Tells whether the battery/supercap of the RTC (if any) is
+	chargeable or not.
+	Possible values are 0 (not chargeable), 1 (chargeable)
+
+Deprecated properties:
+- trickle-diode-disable : ds1339, ds1340 and ds1388 only
 	Do not use internal trickle charger diode
 	Should be given if internal trickle charger diode should be disabled
+	(superseded by aux-voltage-chargeable)
 
 Example:
 	ds1339: rtc@68 {