MIPS: DTS: jz4780: add #clock-cells to rtc_dev

This makes the driver present the clk32k signal if requested.
It is needed to clock the PMU of the BCM4330 WiFi and Bluetooth
module of the CI20 board.
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/boot/dts/ingenic/jz4780.dtsi

@@ -155,6 +155,8 @@ rtc_dev: rtc@10003000 {
 
 		clocks = <&cgu JZ4780_CLK_RTCLK>;
 		clock-names = "rtc";
+
+		#clock-cells = <0>;
 	};
 
 	pinctrl: pin-controller@10010000 {