UPSTREAM: device connection: Add fwnode member to struct device_connection

This will prepare the device connection API for connections
described in firmware.

Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Jun Li <jun.li@nxp.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 09aa11cfda9d8186046bcd1adcd6498b688114f4)
Signed-off-by: Connor O'Brien <connoro@google.com>
Bug: 150958419
Change-Id: Ia44efefed94198c36b52624fb9e2f5cbf24a996c