Add support for ASUS RT-AX89X AX6000

For Developers
336

To set a fixed fan speed, you need to add a few lines to file rc.local (LuCI -> System -> Startup):

for file in /sys/class/thermal/thermal_zone*/mode; do
  echo disabled > "$file";
done
echo 1600 > /sys/class/hwmon/hwmon0/fan1_target