drm/msm/dpu: Fix pixel extension sub-sampling

drm/msm/dpu: Fix pixel extension sub-sampling

In _dpu_plane_setup_pixel_ext function instead of dividing just chroma
source resolution once (component 1 and 2), second component is divided
once more because src_w and src_h variable is reused between iterations.
Third component receives wrong source resolution too (from component 2).
To fix this introduce temporary variables for each iteration.

Fixes: dabfdd89eaa9 ("drm/msm/disp/dpu1: add inline rotation support for sc7280")
Signed-off-by: Vladimir Lypak <vladimir.lypak@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/681921/
Link: https://lore.kernel.org/r/20251017-b4-dpu-fixes-v1-4-40ce5993eeb6@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>