Move properties common to all MDSS DT nodes to the mdss-common.yaml.

This extends qcom,msm8998-mdss schema to allow interconnect nodes, which
will be added later, once msm8998 gains interconnect support.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/508385/
Link: https://lore.kernel.org/r/20221024164225.3236654-6-dmitry.baryshkov@linaro.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>