USB: quatech2: always disable uart on close

Always try to disable the uart on close.

Since the switch to tty ports, close will be called as part of shutdown
before disconnect returns. Hence there is no need to check the
disconnected flag, and we can put devices in disabled states also on
driver unbind.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/quatech2.c

@@ -422,12 +422,6 @@ static void qt2_close(struct usb_serial_port *port)
 	port_priv->urb_in_use = false;
 	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
 
-	mutex_lock(&port->serial->disc_mutex);
-	if (port->serial->disconnected) {
-		mutex_unlock(&port->serial->disc_mutex);
-		return;
-	}
-
 	/* flush the port transmit buffer */
 	i = usb_control_msg(serial->dev,
 			    usb_rcvctrlpipe(serial->dev, 0),
@@ -458,8 +452,6 @@ static void qt2_close(struct usb_serial_port *port)
 	if (i < 0)
 		dev_err(&port->dev, "%s - close port failed %i\n",
 			__func__, i);
-
-	mutex_unlock(&port->serial->disc_mutex);
 }
 
 static void qt2_disconnect(struct usb_serial *serial)