[PATCH] Fix NULL pointer dereference in isdn_tty_at_cout

The changes in the tty related code introduced wrong parenthesis in a if
condition in the isdn_tty_at_cout function.  This caused access to index -1
in the dev->drv[] array.  This patch change it back to the correct
condition from the previous versions.
Signed-off-by: NKarsten Keil <kkeil@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/isdn/i4l/isdn_tty.c

@@ -2359,8 +2359,8 @@ isdn_tty_at_cout(char *msg, modem_info * info)
 
 	/* use queue instead of direct, if online and */
 	/* data is in queue or buffer is full */
-	if ((info->online && tty_buffer_request_room(tty, l) < l) ||
-	    (!skb_queue_empty(&dev->drv[info->isdn_driver]->rpqueue[info->isdn_channel]))) {
+	if (info->online && ((tty_buffer_request_room(tty, l) < l) ||
+	    !skb_queue_empty(&dev->drv[info->isdn_driver]->rpqueue[info->isdn_channel]))) {
 		skb = alloc_skb(l, GFP_ATOMIC);
 		if (!skb) {
 			spin_unlock_irqrestore(&info->readlock, flags);