USB: metro-usb: fix tty_flip_buffer_push use

Do not set low_latency flag at open as tty_flip_buffer_push must not be
called in IRQ context with low_latency set.

Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/metro-usb.c

@@ -222,14 +222,6 @@ static int metrousb_open(struct tty_struct *tty, struct usb_serial_port *port)
 	metro_priv->throttled = 0;
 	spin_unlock_irqrestore(&metro_priv->lock, flags);
 
-	/*
-	 * Force low_latency on so that our tty_push actually forces the data
-	 * through, otherwise it is scheduled, and with high data rates (like
-	 * with OHCI) data can get lost.
-	 */
-	if (tty)
-		tty->low_latency = 1;
-
 	/* Clear the urb pipe. */
 	usb_clear_halt(serial->dev, port->interrupt_in_urb->pipe);