Merge pull request #2962 from ljmen/usb_device

add cases for dmi-to-pci-bridge controller

libvirt/tests/cfg/usb_device.cfg

@@ -21,7 +21,11 @@
                         - pcie-switch-upstream-port:
                             bus_controller = "pcie-root,pcie-root-port,pcie-switch-upstream-port,pcie-switch-downstream-port"
                 - dmi-to-pci-bridge:
-                    bus_controller = "pcie-root,dmi-to-pci-bridge,pci-bridge"
+                    variants:
+                        - dmi-to-pci-bridge:
+                            bus_controller = "pcie-root,dmi-to-pci-bridge"
+                        - pci-bridge:
+                            bus_controller = "pcie-root,dmi-to-pci-bridge,pci-bridge"
         - pci-root:
             only i440fx
             bus_controller = "pci-root,pci-bridge"