pciutils: Add decoding of vendor specific VPD fields

pciutils: Add decoding of vendor specific VPD fields

IBM has defined several VPD fields that are not part of the PCI
spec, but are frequently used on embedded and pluggable pcie
adapters.

Since these fields are "Unknown", they are listed in hex
and less readable.

This patch adds commonly used vendor specific VPD keywords
described in "Table 160. LoPAPR VPD Fields" of the Linux on Power
Architecture Platform Reference (LoPAPR).

Signed-off-by: John Walthour <return.0@me.com>