arm64: dts: rockchip: add adc joystick to Odroid Go Advance

Add the now usable adc-joystick node that describes the analog
joystick connected to two saradc channels from the rk3326 soc.
Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Link: https://lore.kernel.org/r/20200703221413.269800-1-heiko@sntech.de

arch/arm64/boot/dts/rockchip/rk3326-odroid-go2.dts

@@ -18,6 +18,30 @@ chosen {
 		stdout-path = "serial2:115200n8";
 	};
 
+	adc-joystick {
+		compatible = "adc-joystick";
+		io-channels = <&saradc 1>,
+			      <&saradc 2>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		axis@0 {
+			reg = <0>;
+			abs-flat = <10>;
+			abs-fuzz = <10>;
+			abs-range = <172 772>;
+			linux,code = <ABS_X>;
+		};
+
+		axis@1 {
+			reg = <1>;
+			abs-flat = <10>;
+			abs-fuzz = <10>;
+			abs-range = <278 815>;
+			linux,code = <ABS_Y>;
+		};
+	};
+
 	backlight: backlight {
 		compatible = "pwm-backlight";
 		power-supply = <&vcc_bl>;