ntb_hw_switchtec: Expand PFF CSR registers

The PFF CSR registers actual mirrors the PCI configuration space
for all the ports in the switch. Previously, this was not needed by
the driver but will be used by the crosslink code to enumerate the
bus in an host-less centre partition.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>