drm/msm/dpu: rework plane CSC setting

Rework the code flushing CSC settings for the plane. Separate out the
pipe and pipe_cfg as a preparation for r_pipe support.

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Tested-by: Abhinav Kumar <quic_abhinavk@quicinc.com> # sc7280
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/527347/
Link: https://lore.kernel.org/r/20230316161653.4106395-25-dmitry.baryshkov@linaro.org


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