ARM: dts: koelsch: Add CEC clock for HDMI transmitter

The adv7511 on the Koelsch board has a 12 MHz fixed clock
for the CEC block. Specify this in the dts to enable CEC support.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7791-koelsch.dts

@@ -642,11 +642,19 @@
 		};
 	};
 
+	cec_clock: cec-clock {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <12000000>;
+	};
+
 	hdmi@39 {
 		compatible = "adi,adv7511w";
 		reg = <0x39>;
 		interrupt-parent = <&gpio3>;
 		interrupts = <29 IRQ_TYPE_LEVEL_LOW>;
+		clocks = <&cec_clock>;
+		clock-names = "cec";
 
 		adi,input-depth = <8>;
 		adi,input-colorspace = "rgb";