ARM: sun6i: Add UART0 muxing options

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun6i-a31.dtsi

@@ -76,6 +76,13 @@
 			#address-cells = <1>;
 			#size-cells = <0>;
 			#gpio-cells = <3>;
+
+			uart0_pins_a: uart0@0 {
+				allwinner,pins = "PH20", "PH21";
+				allwinner,function = "uart0";
+				allwinner,drive = <0>;
+				allwinner,pull = <0>;
+			};
 		};
 
 		timer@01c20c00 {