arm64: dts: r8a7796: m3ulcb: Add DU external dot clocks

The DU0/DU1/DU2 external dot clocks are provided by the programmable
Versaclock5 clock generator.
Signed-off-by: Vladimir Barinov <vladimir.barinov+renesas@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7796-m3ulcb.dts

@@ -28,3 +28,15 @@ memory@600000000 {
 		reg = <0x6 0x00000000 0x0 0x40000000>;
 	};
 };
+
+&du {
+	clocks = <&cpg CPG_MOD 724>,
+		 <&cpg CPG_MOD 723>,
+		 <&cpg CPG_MOD 722>,
+		 <&cpg CPG_MOD 727>,
+		 <&versaclock5 1>,
+		 <&versaclock5 3>,
+		 <&versaclock5 2>;
+	clock-names = "du.0", "du.1", "du.2", "lvds.0",
+		      "dclkin.0", "dclkin.1", "dclkin.2";
+};