net, TTY: initialize tty->driver_data before usage

Commit 9c650ff ("TTY: ircomm_tty, add tty install") split _open() to
_install() and _open(). It also moved the initialization of driver_data
out of open(), but never added it to install() - causing a NULL ptr
deref whenever the driver was used.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/irda/ircomm/ircomm_tty.c

@@ -421,6 +421,8 @@ static int ircomm_tty_install(struct tty_driver *driver, struct tty_struct *tty)
 		hashbin_insert(ircomm_tty, (irda_queue_t *) self, line, NULL);
 	}
 
+	tty->driver_data = self;
+
 	return tty_port_install(&self->port, driver, tty);
 }