PCI/VPD: Move VPD quirks to vpd.c

Move the VPD-related quirks from quirks.c to vpd.c, which removes the need
for struct pci_vpd outside vpd.c.  The goal is to encapsulate all the VPD
code and structures in vpd.c.

No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>