Unable to find Serial Number of Dragonboard 845(RB3)

Hello ,
I am trying to replicate a project according to https://git.linaro.org/people/srinivas.kandagatla/ImagenetCv.git/tree/README?h=camera.
In the Step 2) ##Get serial number from the DB845c console using below command and pass it to elfsigner.py.
The command cat /sys/bus/soc/devices/soc0/serial_number doesnt give me the serial number.
I do not have a folder structure similar to /sys/bus/soc/devices/soc0/ .
Tried looking for the serial_number file in the /sys directory, it only shows serial numbers of USBs and PCIs, but not the serial_number of the board.

Please find the screenshot below:

.

OS = Debian GNU/Linux 10 (buster)
Kernel = Linux 5.2.0-qcomlt-arm64

Can anyone help me get through this issue?
Thanks

Which release are you running? the 19.09 release does not have the serial_number SoC property, the 19.11 should work.