platform/chrome: cros_ec_typec: Clear Type C disc events

Clear USB Type C discovery events from the Chrome EC once they've been
successfully handled.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reported-by: Benson Leung <bleung@chromium.org>
Tested-by: Benson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20210203021539.745239-2-pmalani@chromium.org


Signed-off-by: Benson Leung <bleung@chromium.org>