thunderbolt: Add details to router uevent

Expose two environment variables for routers as part of the initial
uevent:

  USB4_VERSION=1.0
  USB4_TYPE=host|device|hub

Userspace can use this information to expose more details about each
connected device. Only USB4 devices have USB4_VERSION but all devices
have USB4_TYPE.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>