ARM: sun9i: optimus: Set UART0 muxing

Enable the UART0 muxing, as set up by the bootloader.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

arch/arm/boot/dts/sun9i-a80-optimus.dts

@@ -60,6 +60,8 @@ chosen {
 
 	soc {
 		uart0: serial@07000000 {
+			pinctrl-names = "default";
+			pinctrl-0 = <&uart0_pins_a>;
 			status = "okay";
 		};
 	};

arch/arm/boot/dts/sun9i-a80.dtsi

@@ -351,6 +351,13 @@ pio: pinctrl@06000800 {
 			#interrupt-cells = <2>;
 			#size-cells = <0>;
 			#gpio-cells = <3>;
+
+			uart0_pins_a: uart0@0 {
+				allwinner,pins = "PH12", "PH13";
+				allwinner,function = "uart0";
+				allwinner,drive = <0>;
+				allwinner,pull = <0>;
+			};
 		};
 
 		uart0: serial@07000000 {