fallback to device-tree when DMI informations are not available to fetch serial product

[EdouardVanbelle]

Please find a fallback to device-tree norm when DMI informations are not available

more details:

• https://www.kernel.org/doc/html/latest/devicetree/usage-model.html
• https://www.devicetree.org/specifications/

I only added informations on Product section, device-tree may be usable on other additional devices

Example on an old R-Pi device:
Before:

$ sudo ./sysinfo | jq -r .product
{
  "uuid": "00000000-0000-0000-0000-000000000000"
}

After:

$ sudo ./sysinfo | jq -r .product
{
  "name": "Raspberry Pi 3 Model B Rev 1.2",
  "serial": "00000000279****",
  "uuid": "00000000-0000-0000-0000-000000000000"
}

[zcalusic]

LGTM, thank you for your contribution!