dt-bindings: media: csi: Add interconnects properties

The Allwinner CSI controller is sitting beside the MBUS that is represented
as an interconnect.

Make sure that the interconnect properties are valid in the binding.

Fixes: 7866d690

 ("media: dt-bindings: media: sun4i-csi: Add compatible for CSI0 on R40")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Rob Herring <robh@kernel.org>