drm/msm/dpu: remove unused dpu_hw_blk features

drm/msm/dpu: remove unused dpu_hw_blk features

Remove all unused dpu_hw_blk features and functions:
- dpu_hw_blk_get()/_put() and respective refcounting,
- global list of all dpu_hw_blk instances,
- dpu_hw_blk_ops and empty implementation inside each hw_blk subdriver.

This leaves dpu_hw_blk as a placeholder with just type and index.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210515190909.1809050-2-dmitry.baryshkov@linaro.org
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>