vt: always call notifier with the console lock held

commit 7e1d2263 upstream.

Every invocation of notify_write() and notify_update() is performed
under the console lock, except for one case. Let's fix that.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/vt.c

@@ -2767,8 +2767,8 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
 	con_flush(vc, draw_from, draw_to, &draw_x);
 	vc_uniscr_debug_check(vc);
 	console_conditional_schedule();
-	console_unlock();
 	notify_update(vc);
+	console_unlock();
 	return n;
 }