arm64: dts: qcom: sm8350: Add mdss_ prefix to DSIn out labels

Add the mdss_ prefix to DSIn labels, so that the hardware blocks can
be organized near each other while retaining the alphabetical order
in device DTs when referencing by label.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230120210101.2146852-7-konrad.dybcio@linaro.org