usb: typec: Declare the typec_class static

This is only to make the handling of the class consistent
with the two other susbsystems - the alt mode bus and the
mux class.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20210401105847.13026-3-heikki.krogerus@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>