arm64: dts: qcom: sdm845: Don't disable MDP explicitly

DPU/MDSS is borderline useless without MDP, so disabling
both of them makes little sense. With this change, enabling
mdss will be enough.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211002001358.45920-4-konrad.dybcio@somainline.org