This is a cleanup part of the DPU multirect patchset [1], split away to ease review and merging per Abhinav's request.
Currently significant part of atomic plane state is stored in the drm_plane's subclass rather than drm_plane_state's subclass. Move it either to the drm_plane_state or even to the on-stack allocation. [1] https://lore.kernel.org/linux-arm-msm/20210705012115.4179824-1-dmitry.barysh...@linaro.org/
