PCI/VPD: Clean up public VPD defines and inline functions

After recent introduction of new VPD API functions and user migration
these defines and inline functions aren't used outside VPD core any
longer.

Link: https://lore.kernel.org/r/d33e06bf-bc5e-ece7-bf35-7245ae224d1b@gmail.com


Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>