Add support for "address type 6"

[Nieuwejaar]

On the asilomar config for madrid, we are failing to parse the LLDPDUs from the Cisco switch:

01:29:00.979Z ERRO lldpd: parsing LLDP packet failed: Protocol("unsupported address type 6 in TLV")
    iface = tfportqsfp15_0                                
    port = qsfp15/0 

We should add support for this address type. We should also improve the error reporting, so we know which TLV it is attempting to parse. The address type can be used in multiple fields, and this doesn't tell us which one.