dt-bindings: phy: samsung,mipi-video-phy: deprecate syscon phandle

The MIPI phy is actually part of the Power Management Unit system
controller, thus it should be its child, instead of sibling node with
syscon phandle.

Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230127194057.186458-4-krzysztof.kozlowski@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>