PCI/sysfs: Rename "vpd" attribute accessors

Rename "vpd" attribute accessors so they fit with the BIN_ATTR_RW() macro
usage.  Currently there is no BIN_ATTR_ADMIN_RW() that uses 0600
permissions, but if there were, it would likely use "vpd_read()" and
"vpd_write()".  No functional change intended.

Extracted from the patch mentioned below by Heiner Kallweit
<hkallweit1@gmail.com>.

Link: https://lore.kernel.org/linux-pci/7703024f-8882-9eec-a122-599871728a89@gmail.com/


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>