[Why] The dc_fast_update intermediate struct created code duplication and complexity with multiple classification paths (populate_fast_updates, fast_nonaddr_updates_exist, full_update_required). This refactoring simplifies the update classification system by consolidating to a single path while maintaining compatibility. [How] Remove entire dc_fast_update struct and associated helper functions: - populate_fast_updates - fast_nonaddr_updates_exist - full_update_required Refactor check_update_surfaces_for_stream as the single classification path with explicit handling for func_shaper, lut3d_func, cursor_csc_color_matrix_change, and scaler_sharpener_update. Add a reserved bitfield to the stream_update_flags union for completeness guards. Extract dc_check_address_only_update and dc_check_update_surfaces_for_stream as public. Reviewed-by: Alvin Lee <alvin.lee2@amd.com> Signed-off-by: Rafal Ostrowski <rafal.ostrowski@amd.com> Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>