PCI/VPD: Stop exporting pci_vpd_find_info_keyword()

Now that the last users have been migrated to pci_vpd_find_ro_keyword()
we can stop exporting this function. It's still used in VPD core code.

Link: https://lore.kernel.org/r/96ca2a56-383e-9b61-9cba-4f1e5611dc15@gmail.com


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