How to pass device serialnumber from nvmem to cpuinfo?

I'd like to get device serial number to store it properly: to show in /proc/cpuinfo, /sys/firmware/.../serial-number etc.
I know where it stored in my device MTD : it is stored in factory partition at offset 0xe100, and it is a quoted string like "12345...."\0. I assume it can take up to 32 bytes (in my case it is 21 bytes including quotes).
But I could not set it in DTS file.