dt-bindings: display/msm: Add binding for SC8280XP MDSS

Add binding for the display subsystem and display processing unit in the
Qualcomm SC8280XP platform.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/514396/
Link: https://lore.kernel.org/r/20221207220012.16529-2-quic_bjorande@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>