hso: remove setting of low_latency flag

This patch removes the setting of the low_latency flag. 
tty_flip_buffer_push() is occasionally being called in irq context, which 
causes a hang if the low_latency flag is set.
Removing the low_latency flag only seems to impact the flush to ldisc, 
which will now be put on a workqueue.
Signed-off-by: NFilip Aben <f.aben@option.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/hso.c

@@ -1334,7 +1334,6 @@ static int hso_serial_open(struct tty_struct *tty, struct file *filp)
 	/* check for port already opened, if not set the termios */
 	serial->open_count++;
 	if (serial->open_count == 1) {
-		tty->low_latency = 1;
 		serial->rx_state = RX_IDLE;
 		/* Force default termio settings */
 		_hso_serial_set_termios(tty, NULL);