platform/chrome: cros_ec_typec: Register partner altmodes

Use the discovery data from the Chrome EC to register parter altmodes
with the Type C Connector Class framework. Also introduce a node
struct to keep track of the list of registered alt modes.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201029222738.482366-8-pmalani@chromium.org