drm/msm/dpu: calculate data_width like downstream

drm/msm/dpu: calculate data_width like downstream

Derive INTF data_width from dce_bytes_per_line rather than
timing->width when DSC is enabled. Use DIV_ROUND_UP to avoid
rounding errors.

Signed-off-by: Alexander Koskovich <akoskovich@pm.me>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Tested-by: Pengyu Luo <mitltlatltl@gmail.com> # Lenovo Legion Y700 Gen4 (SM8750)
Patchwork: https://patchwork.freedesktop.org/patch/713333/
Link: https://lore.kernel.org/r/20260322-fix-data-width-calc-v2-1-d5f28136bc4e@pm.me
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>