usb: typec: class: Don't use port parent for getting mux handles

commit 23481121c81d984193edf1532f5e123637e50903 upstream.

It is not possible to use the parent of the port device when
requesting mux handles as the parent may be a multiport USB
Type-C or PD controller. The muxes must be assigned to the
ports, not the controllers.

This will also move the requesting of the muxes after the
port device is initialized.

Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>