TTY: add ports array to tty_driver

It will hold tty_port structures for all drivers which do not want to
define tty->ops->install hook.

We ignore PTY here because it wants 1 million lines and it installs
tty_port in ->install anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/tty_driver.h

@@ -313,6 +313,7 @@ struct tty_driver {
 	 * Pointer to the tty data structures
 	 */
 	struct tty_struct **ttys;
+	struct tty_port **ports;
 	struct ktermios **termios;
 	void *driver_state;