USB: removal of tty->low_latency hack dating back to the old serial code

This removes tty->low_latency from all USB serial drivers that push
data into the tty layer at hard interrupt context. It's no longer needed
and actually harmful.

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/ipaq.c

@@ -631,13 +631,7 @@ static int ipaq_open(struct tty_struct *tty,
 		priv->free_len += PACKET_SIZE;
 	}
 
-	/*
-	 * Force low latency on. This will immediately push data to the line
-	 * discipline instead of queueing.
-	 */
-
 	if (tty) {
-		tty->low_latency = 1;
 		/* FIXME: These two are bogus */
 		tty->raw = 1;
 		tty->real_raw = 1;