dt-bindings: display: msm: Add binding for msm8998 dpu

Add yaml binding for msm8998 dpu1 support.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Jami Kettunen <jami.kettunen@somainline.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220113145111.29984-4-jami.kettunen@somainline.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>