PCI/VPD: Correct diagnostic for VPD read failure

Previously, when a VPD read failed, we warned about an "invalid large
VPD tag".  Warn about the VPD read failure instead.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>