cxgb3: Remove t3_seeprom_read and use VPD API

cxgb3: Remove t3_seeprom_read and use VPD API

Using the VPD API allows to simplify the code and completely get rid
of t3_seeprom_read(). Note that we don't have to use pci_read_vpd_any()
here because a VPD quirk sets dev->vpd.len to the full EEPROM size.

Tested with a T320 card.

Link: https://lore.kernel.org/r/68ef15bb-b6bf-40ad-160c-aaa72c4a70f8@gmail.com
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>