PCI/VPD: Remove struct pci_vpd.flag

The struct pci_vpd.flag member was used only to communicate between
pci_vpd_wait() and its callers.  Remove the flag member and pass the value
directly to pci_vpd_wait() to simplify the code.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/e4ef6845-6b23-1646-28a0-d5c5a28347b6@gmail.com
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>