console: dummycon: export dummycon_[un]register_output_notifier

Export dummycon_[un]register_output_notifier, the fbcon code needs this
and may be build as a module.

Fixes: 83d83beb ("console/fbcon: Add support for deferred console takeover")
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

drivers/video/console/dummycon.c

@@ -38,11 +38,13 @@ void dummycon_register_output_notifier(struct notifier_block *nb)
 	if (dummycon_putc_called)
 		nb->notifier_call(nb, 0, NULL);
 }
+EXPORT_SYMBOL_GPL(dummycon_register_output_notifier);
 
 void dummycon_unregister_output_notifier(struct notifier_block *nb)
 {
 	raw_notifier_chain_unregister(&dummycon_output_nh, nb);
 }
+EXPORT_SYMBOL_GPL(dummycon_unregister_output_notifier);
 
 static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
 {