s390x/pci: fix endianness issues

s390x/pci: fix endianness issues

The zPCI group and function structures are big endian. However, we do
not consistently store them as big endian locally, and are missing some
conversions.

Let's just store the structures as host endian instead and convert to
big endian when actually handling the instructions retrieving the data.

Also fix the layout of ClpReqQueryPciGrp: g is actually only 8 bit. This
also fixes accesses on little endian hosts, and makes accesses on big
endian hosts consistent.

Fixes: 28dc86a07299 ("s390x/pci: use a PCI Group structure")
Fixes: 9670ee752727 ("s390x/pci: use a PCI Function structure")
Fixes: 1e7552ff5c34 ("s390x/pci: get zPCI function info from host")
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20201118104202.1301363-1-cohuck@redhat.com>