overlays: i2c-rtc-gpio: Fix trickle-resistor-ohms param

The abx80x implementation of the trickle-resistor-ohms parameter is
missing the ":0" indicating that the target is an integer/cell value.

See: raspberrypi/linux#3642

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

arch/arm/boot/dts/overlays/i2c-rtc-gpio-overlay.dts

@@ -230,7 +230,7 @@
 
 		trickle-diode-type = <&abx80x>,"abracon,tc-diode";
 		trickle-resistor-ohms = <&ds1339>,"trickle-resistor-ohms:0",
-					<&abx80x>,"abracon,tc-resistor",
+					<&abx80x>,"abracon,tc-resistor:0",
 					<&rv3028>,"trickle-resistor-ohms:0";
 		backup-switchover-mode = <&rv3028>,"backup-switchover-mode:0";
 		wakeup-source = <&ds1339>,"wakeup-source?",