Use pci_vpd_find_id_string() to find the VPD ID string. This simplifies the
code and avoids the need for pci_vpd_lrdt_size().

Link: https://lore.kernel.org/r/19ea2e9b-6e94-288a-6612-88db01b1b417@gmail.comSigned-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>