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

The S3C RTC requires 32768 Hz clock as input which is provided by PMIC.
However there is no such clock provider but rather a regulator driver
which registers the clock as a regulator. This is an old driver which
will not be updated so add a workaround - a fixed-clock to fill missing
clock phandle reference in S3C RTC.

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-aquila.dts

···
 			0x40000000 0x18000000>;
 	};
 
+	pmic_ap_clk: clock-0 {
+		/* Workaround for missing clock on PMIC */
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <32768>;
+	};
+
 	regulators {
 		compatible = "simple-bus";
 		#address-cells = <1>;
···
 					regulator-always-on;
 				};
 
+				ap32khz_reg: EN32KHz-AP {
+					regulator-name = "32KHz AP";
+					regulator-always-on;
+				};
+
 				vichg_reg: ENVICHG {
 					regulator-name = "VICHG";
 				};
···
 
 &uart3 {
 	status = "okay";
+};
+
+&rtc {
+	clocks = <&clocks CLK_RTC>, <&pmic_ap_clk>;
+	clock-names = "rtc", "rtc_src";
 };
 
 &sdhci0 {