drm/msm/dpu: use PINGPONG_NONE for LMs with no PP attached

On msm8998/sdm845 some LM blocks do not have corresponding PINGPONG
block. Currently the driver uses PINGPONG_MAX for such cases. Switch
that to use PINGPONG_NONE instead, which is more logical.

Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/538205/
Link: https://lore.kernel.org/r/20230519234025.2864377-4-dmitry.baryshkov@linaro.org


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