When I submitted the extcon handling I had a patch pending for the
extcon sub-system for extcon_register_notifier to take -1 as cable id
for listening for all type cable events on an extcon with a single
notifier.

In the end it was decided to instead add a new
extcon_register_notifier_all function for this, switch to using this.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Liam Breck <kernel@networkimprov.net>
Signed-off-by: Sebastian Reichel <sre@kernel.org>