ARM: sunxi: dt: Add uart3 dt node

Both A10 and A13 Allwinner SoCs have a Synopsys APB uart3 device
available, so add it to the sunxi.dtsi file
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Emilio López <emilio@elopez.com.ar>

arch/arm/boot/dts/sunxi.dtsi

@@ -145,5 +145,15 @@ uart1: serial@01c28400 {
 			clocks = <&osc>;
 			status = "disabled";
 		};
+
+		uart3: serial@01c28c00 {
+			compatible = "snps,dw-apb-uart";
+			reg = <0x01c28c00 0x400>;
+			interrupts = <4>;
+			reg-shift = <2>;
+			reg-io-width = <4>;
+			clocks = <&osc>;
+			status = "disabled";
+		};
 	};
 };