gallium: Stop exposing ->set_damage_region()
The partial_update() infra is broken and needs fixing at the gallium core level: the BACK_LEFT attachment can be outdated when the user calls KHR_partial_update(), leading to a damage region update on the wrong pipe_resource object. Let's not implement ->set_damage_region() until the core is fixed to handle that properly.
For the record, the original revert (the one that broke Lima build) is here . I also sent an RFC  that was solving the problem in a hack-ish way, but couldn't find a solution that would work without passing a DRIContext to ->set_damage_region(). Would be great if DRI/Gallium experts (@mareko?) could help me with that.
This MR superseeds !2673 (closed).