drm/amdgpu: Fix warning in dma_fence_is_later on resume from S3.

Problem:
amdgpu_ttm_set_buffer_funcs_status destroys adev->mman.entity on suspend
without releasing adev->mman.bdev.man[TTM_PL_VRAM].move fence
so on resume the new drm_sched_entity.fence_context causes
the warning against the old fence context which is different.

Fix:
When destroying sched_entity in amdgpu_ttm_set_buffer_funcs_status
release  man->move and set the pointer to NULL.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -1927,6 +1927,8 @@ void amdgpu_ttm_set_buffer_funcs_status(struct amdgpu_device *adev, bool enable)
 	} else {
 		drm_sched_entity_destroy(adev->mman.entity.sched,
 					 &adev->mman.entity);
+		dma_fence_put(man->move);
+		man->move = NULL;
 	}
 
 	/* this just adjusts TTM size idea, which sets lpfn to the correct value */