staging: serqt_usb2: remove unneeded return in qt_throttle

this return is in the end of the qt_throttle function, so this return
not needed
Signed-off-by: Devendra Naga <develkernel412222@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/serqt_usb2/serqt_usb2.c

@@ -1458,7 +1458,6 @@ static void qt_throttle(struct tty_struct *tty)
 	qt_port->RxHolding = 1;
 
 	mutex_unlock(&qt_port->lock);
-	return;
 }
 
 static void qt_unthrottle(struct tty_struct *tty)