dt-bindings: display/msm: Add SM6375 MDSS

Document the SM6375 MDSS.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/541289/
Link: https://lore.kernel.org/r/20230411-topic-straitlagoon_mdss-v6-5-dee6a882571b@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>