drm/msm/dpu: Fix adjusted mode clock check for 3d merge

drm/msm/dpu: Fix adjusted mode clock check for 3d merge

Since 3D merge allows for larger modes to be supported across 2 layer
mixers, filter modes based on adjusted mode clock / 2 when 3d merge is
supported.

Reported-by: Abel Vesa <abel.vesa@linaro.org>
Fixes: 62b7d6835288 ("drm/msm/dpu: Filter modes based on adjusted mode clock")
Signed-off-by: Jessica Zhang <jessica.zhang@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Tested-by: Abel Vesa <abel.vesa@linaro.org>
Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/676353/
Link: https://lore.kernel.org/r/20250923-modeclk-fix-v2-1-01fcd0b2465a@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>