Not include system ROM as RAM Module

[slamora]

Device inventory doesn't exclude DMI decode Memory Module entry with Form factor = Chip and handles it as a RAM Module (e.g. Form factor = DIMM).

This bug affects a devices like "HP Compaq dc5800 Microtower" (e.g. CZC7345F3Z, CZC82108PL, CZC82108PZ) which include a RamModule component without serialNumber:

    {
        "@type": "RamModule", 
        "interface": "DDR2", 
        "size": 4096
    }