qemu: Error out on invalid pci-root controller model name

This is a hard error, and should be handled as such.
Introduced in 24614760.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/qemu/qemu_domain.c

@@ -4446,7 +4446,7 @@ qemuDomainDeviceDefValidateControllerPCI(const virDomainControllerDef *controlle
                            _("PCI controller model name '%s' is not valid "
                              "for a pci-root"),
                            modelName);
-            return 0;
+            return -1;
         }
 
         if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_SPAPR_PCI_HOST_BRIDGE)) {