ARM: dts: sun9i: Enable uart4 for A80 Optimus board

The A80 Optimus board exposes uart4 on the GPIO expansion header.
Enable it so we can use it.

Also enable the internal pull-ups, as there doesn't seem to be
external pull-up resistors for pins on the expansion header.
Signed-off-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

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

@@ -71,6 +71,11 @@
 				allwinner,drive = <0>;
 				allwinner,pull = <0>;
 			};
+
+			uart4_pins_a: uart4@0 {
+				/* Enable internal pull-up */
+				allwinner,pull = <1>;
+			};
 		};
 
 		uart0: serial@07000000 {
@@ -79,6 +84,12 @@
 			status = "okay";
 		};
 
+		uart4: serial@07001000 {
+			pinctrl-names = "default";
+			pinctrl-0 = <&uart4_pins_a>;
+			status = "okay";
+		};
+
 		i2c3: i2c@07003400 {
 			pinctrl-names = "default";
 			pinctrl-0 = <&i2c3_pins_a>;