Fix leak of usbDevice struct when initializing cgroups

When iterating over USB host devices to setup cgroups, the
usbDevice object was leaked in both LXC and QEMU driers
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/lxc/lxc_cgroup.c

@@ -427,8 +427,11 @@ static int virLXCCgroupSetupDeviceACL(virDomainDefPtr def,
                 goto cleanup;
 
             if (usbDeviceFileIterate(usb, virLXCSetupHostUsbDeviceCgroup,
-                                     cgroup) < 0)
+                                     cgroup) < 0) {
+                usbFreeDevice(usb);
                 goto cleanup;
+            }
+            usbFreeDevice(usb);
             break;
         case VIR_DOMAIN_HOSTDEV_MODE_CAPABILITIES:
             switch (hostdev->source.caps.type) {

src/qemu/qemu_cgroup.c

@@ -302,8 +302,11 @@ int qemuSetupCgroup(virQEMUDriverPtr driver,
                 goto cleanup;
 
             if (usbDeviceFileIterate(usb, qemuSetupHostUsbDeviceCgroup,
-                                     &data) < 0)
+                                     &data) < 0) {
+                usbFreeDevice(usb);
                 goto cleanup;
+            }
+            usbFreeDevice(usb);
         }
     }