ARM: shmobile: r8a7794: Add DU node to device tree

Add the DU device with a disabled state. Boards that want to enable the
DU need to specify the output topology.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7794.dtsi

@@ -750,6 +750,34 @@ usb2: usb-channel@2 {
 		};
 	};
 
+	du: display@feb00000 {
+		compatible = "renesas,du-r8a7794";
+		reg = <0 0xfeb00000 0 0x40000>;
+		reg-names = "du";
+		interrupts = <0 256 IRQ_TYPE_LEVEL_HIGH>,
+			     <0 268 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&mstp7_clks R8A7794_CLK_DU0>,
+			 <&mstp7_clks R8A7794_CLK_DU0>;
+		clock-names = "du.0", "du.1";
+		status = "disabled";
+
+		ports {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			port@0 {
+				reg = <0>;
+				du_out_rgb0: endpoint {
+				};
+			};
+			port@1 {
+				reg = <1>;
+				du_out_rgb1: endpoint {
+				};
+			};
+		};
+	};
+
 	clocks {
 		#address-cells = <2>;
 		#size-cells = <2>;