PCI/VPD: Make missing VPD message less alarming

PCI/VPD: Make missing VPD message less alarming

Realtek RTL8169/8168/8125 NIC families indicate VPD capability and an
optional VPD EEPROM can be connected via I2C/SPI. However I haven't seen
any card or system with such a VPD EEPROM yet. The missing EEPROM causes
the following warning whenever e.g. lscpi -vv is executed.

  invalid short VPD tag 00 at offset 01

The warning confuses users, and I think we should handle the situation more
gently. Therefore, if first VPD byte is read as 0x00, assume a missing
optional VPD PROM and replace the warning with a more descriptive message
at info level.

[bhelgaas: fix pre-existing whitespace]
Link: https://lore.kernel.org/r/ccbc11f1-4dbb-e2c8-d0ea-559e06d4c340@gmail.com
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>