Revert "drm/amd: flush any delayed gfxoff on suspend entry"

In the Linux kernel, the following vulnerability has been resolved:

Revert "drm/amd: flush any delayed gfxoff on suspend entry"

commit ab4750332dbe ("drm/amdgpu/sdma5.2: add begin/end_use ring

callbacks") caused GFXOFF control to be used more heavily and the

codepath that was removed from commit 0dee72639533 ("drm/amd: flush any

delayed gfxoff on suspend entry") now can be exercised at suspend again.

Users report that by using GNOME to suspend the lockscreen trigger will

cause SDMA traffic and the system can deadlock.

This reverts commit 0dee726395333fea833eaaf838bc80962df886c8.