Gpio sys file I/F isn't shown in WPx5xx Firmware Release 16.1

I need to control of FX30 LED per my indication purpose but its control I/F in sys file system isn’t shown at all in the latest WPx5xx Firmware Release 16.1.
root@fx30s:/sys/class/gpio# ls
export gpiochip1 gpiochip100 gpiochip88 gpiochip94 unexport
According to user guide, gpio47~gpio51 should be shown here for LED control in user space.
I tried FW R16 and R15, but its same. Can you let me know why and which FW version correctly install these gpio control I/F into sysfs or sharing the kernel/bsp source codes for this fix will work for me too.