platform: x86: intel_cht_int33fe: Add connection for the DP alt mode

Adding a connection for the DisplayPort alternate mode.
PI3USB30532 is used for muxing the port to DisplayPort on
CHT platforms. The connection allows the alternate mode
device to get handle to the mux, and therefore make it
possible to use the USB Type-C connector as DisplayPort.

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
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>