s390x/pci: use a PCI Function structure

We use a ClpRspQueryPci structure to hold the information related to a
zPCI Function.

This allows us to be ready to support different zPCI functions and to
retrieve the zPCI function information from the host.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>