usb: u132-hcd: fix potential NULL pointer dereference

In case create_singlethread_workqueue fails, the fix notifies
callers the error to avoid potential NULL pointer dereferences.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/u132-hcd.c

@@ -3203,6 +3203,8 @@ static int __init u132_hcd_init(void)
 		return -ENODEV;
 	printk(KERN_INFO "driver %s\n", hcd_name);
 	workqueue = create_singlethread_workqueue("u132");
+	if (!workqueue)
+		return -ENOMEM;
 	retval = platform_driver_register(&u132_platform_driver);
 	return retval;
 }