TTY: serial_core, remove invalid test

tty->index (named here as line) is set up in initialize_tty_struct.
The value is checked in get_tty_driver for the found driver as:
	if (device < base || device >= base + p->num)
		continue;
	*index = device - base;

So index/line can never be more than driver->num. Hence remove this
test from uart_open.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/serial_core.c

@@ -1529,15 +1529,6 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
 	BUG_ON(!tty_locked());
 	pr_debug("uart_open(%d) called\n", line);
 
-	/*
-	 * tty->driver->num won't change, so we won't fail here with
-	 * tty->driver_data set to something non-NULL (and therefore
-	 * we won't get caught by uart_close()).
-	 */
-	retval = -ENODEV;
-	if (line >= tty->driver->num)
-		goto fail;
-
 	/*
 	 * We take the semaphore inside uart_get to guarantee that we won't
 	 * be re-entered while allocating the state structure, or while we