spapr_pci: encode class code including Prog IF register

Current code missed the Prog IF register. All Class Code, Subclass,
and Prog IF registers are needed to identify the accurate device type.

For example: USB controllers use the PROG IF for denoting: USB
FullSpeed, HighSpeed or SuperSpeed.
Signed-off-by: NNikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppc/spapr_pci.c

@@ -900,8 +900,7 @@ static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
     _FDT(fdt_setprop_cell(fdt, offset, "revision-id",
                           pci_default_read_config(dev, PCI_REVISION_ID, 1)));
     _FDT(fdt_setprop_cell(fdt, offset, "class-code",
-                          pci_default_read_config(dev, PCI_CLASS_DEVICE, 2)
-                            << 8));
+                          pci_default_read_config(dev, PCI_CLASS_PROG, 3)));
     if (pci_default_read_config(dev, PCI_INTERRUPT_PIN, 1)) {
         _FDT(fdt_setprop_cell(fdt, offset, "interrupts",
                  pci_default_read_config(dev, PCI_INTERRUPT_PIN, 1)));