usb: fix usb_qdev_init error handling.

qdev doesn't call the ->exit callback on ->init failures, so we have to
take care ourself that we cleanup property on errors.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/usb-bus.c

@@ -9,6 +9,7 @@ static void usb_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
 
 static char *usb_get_dev_path(DeviceState *dev);
 static char *usb_get_fw_dev_path(DeviceState *qdev);
+static int usb_qdev_exit(DeviceState *qdev);
 
 static struct BusInfo usb_bus_info = {
     .name      = "USB",
@@ -75,12 +76,23 @@ static int usb_qdev_init(DeviceState *qdev, DeviceInfo *base)
     dev->auto_attach = 1;
     QLIST_INIT(&dev->strings);
     rc = usb_claim_port(dev);
-    if (rc == 0) {
-        rc = dev->info->init(dev);
+    if (rc != 0) {
+        goto err;
     }
-    if (rc == 0 && dev->auto_attach) {
+    rc = dev->info->init(dev);
+    if (rc != 0) {
+        goto err;
+    }
+    if (dev->auto_attach) {
         rc = usb_device_attach(dev);
+        if (rc != 0) {
+            goto err;
+        }
     }
+    return 0;
+
+err:
+    usb_qdev_exit(qdev);
     return rc;
 }