PCI: Update VPD definitions

The 'end' tag is actually 0x0f; it's the representation as a small resource
data type tag that's 0x78 (i.e., shifted by 3).  Correct PCI_VPD_STIN_END
and PCI_VPD_SRDT_END accordingly.

Also, add helper functions to extract the resource data type tags for both
large and small resource data types.

[bhelgaas: changelog]
Tested-by: Shane Seymour <shane.seymour@hpe.com>
Tested-by: Babu Moger <babu.moger@oracle.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>