ARM: dts: wpcm450: Add clock controller node

This declares the clock controller and the necessary 48 Mhz reference
clock in the WPCM450 device. Switching devices over to the clock
controller is intentionally done in a separate patch to give time for
the clock controller driver to land.

Signed-off-by: Jonathan Neuschäfer <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Joel Stanley <[e-mail]>

arch/arm/boot/dts/nuvoton-wpcm450.dtsi

···
 		#clock-cells = <0>;
 	};
 
+	refclk: clock-48mhz {
+		/* 48 MHz reference oscillator */
+		compatible = "fixed-clock";
+		clock-output-names = "ref";
+		clock-frequency = <48000000>;
+		#clock-cells = <0>;
+	};
+
 	soc {
 		compatible = "simple-bus";
 		#address-cells = <1>;
···
 		gcr: syscon@b0000000 {
 			compatible = "nuvoton,wpcm450-gcr", "syscon", "simple-mfd";
 			reg = <0xb0000000 0x200>;
+		};
+
+		clk: clock-controller@b0000200 {
+			compatible = "nuvoton,wpcm450-clk";
+			reg = <0xb0000200 0x100>;
+			clocks = <&refclk>;
+			clock-names = "ref";
+			#clock-cells = <1>;
+			#reset-cells = <1>;
 		};
 
 		serial0: serial@b8000000 {