drm/msm/dpu: drop scaler config from plane state

Scaler and pixel_ext configuration does not contain a long living state,
it is used only during plane update, so remove these two fields from
dpu_plane_state and allocate them on stack.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Link: https://lore.kernel.org/r/20211201225140.2481577-2-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>