The size of the VPD area is not necessarily 4-byte aligned, so a
pci_vpd_read() might return less than 4 bytes. Zero our buffer and
accept anything other than an error. Intel X710 NICs exercise this.
Fixes: 4e1a635552d3 ("vfio/pci: Use kernel VPD access functions")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
ce7585f3c4