ARM: dts: s5pv210: add RTC 32 KHz clock in SMDKC110

The S3C RTC requires 32768 Hz clock as input which is provided by PMIC.
However the PMIC is not described in DTS at all so at least add
a workaround to model its clock with a fixed-clock.

This fixes dtbs_check warnings:

rtc@e2800000: clocks: [[2, 145]] is too short
rtc@e2800000: clock-names: ['rtc'] is too short

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/arm/boot/dts/s5pv210-smdkc110.dts

···
 		device_type = "memory";
 		reg = <0x20000000 0x20000000>;
 	};
+
+	pmic_ap_clk: clock-0 {
+		/* Workaround for missing PMIC and its clock */
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <32768>;
+	};
 };
 
 &xusbxti {
···
 
 &rtc {
 	status = "okay";
+	clocks = <&clocks CLK_RTC>, <&pmic_ap_clk>;
+	clock-names = "rtc", "rtc_src";
 };
 
 &i2c0 {