That is easy: plug the USB/Serial CP210x in your Linux machine and run:

# udevadm info -a -n /dev/ttyUSB0 | grep '{serial}' | head -n1

If it is original you will see a complete Unique ID:

# udevadm info -a -n /dev/ttyUSB0 | grep '{serial}' | head -n1 
    ATTRS{serial}=="201794XXXXXXXa11b392c201cf25bb41"

# udevadm info -a -n /dev/ttyUSB0 | grep '{serial}' | head -n1 
    ATTRS{serial}=="fe5e32XXXXXXXa119dec3a1dcf25bb41"

If it is fake probably you will see “0001” as Unique ID:

# udevadm info -a -n /dev/ttyUSB0 | grep '{serial}' | head -n1 
    ATTRS{serial}=="0001"