drm/msm/dpu: remove stage_cfg from struct dpu_crtc

The stage_cfg is not used outside of _dpu_crtc_blend_setup(), so remove
the temporary config from global struct.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Link: https://lore.kernel.org/r/20210930140002.308628-5-dmitry.baryshkov@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>