fwget: improve the pci base script

[bz]

Summary

When matching "class" only match the class byte and not subclass and
programming interface.
Extend the list of supported classes by network, old, and misc (for no
better names on the latter two).
Extend the list of known vendors for various WiFi NICs.
Add a "pci_fixup_class" as some wireless cards have unexpected PCI
classes set. In case we cannot find a matching file for the original
try to see if a "fixed up" version exists. This allows us to avoid
duplicate matching files for the same vendor/driver but different
chipsets.

[bz]

I am really not too keen on adding the "pci_fixup_class" bit but the alternative is splattering semi-empty files including another file for silly silicon.
This also remains one of the concerns I raised on the original review. It feels like something needs to change to avoid adding hacks early on...