udev-builtin-net_id: first parse USB or BCMA identifier, then parse PCI properties

udev-builtin-net_id: first parse USB or BCMA identifier, then parse PCI properties

Previously, we first generate names based on the PCI slot and ACPI
onboard index, and then append an identifier based on USB or BCMA bus
if it exists in between the PCI bus and the interface.

However, if there exists USB or BCMA bus, the name based on the
ACPI onboard index is not used.

So, let's invert the order; first generate USB or BCMA identifier if the
bus exists, then prepend the name with the PCI slot identifier.

With this change, we can drop Names struct, and each naming logic
becomes self-consistent.