drm/amdgpu: flush delete wq after wait fence

[why]
lru_list not empty warning in sw fini during repeated device bind unbind.
There should be a amdgpu_fence_wait_empty() before the flush_delayed_work()
call as Christian suggested.

[how]
Move to do flush_delayed_work for ttm bo delayed delete wq after fence_driver_hw_fini.

Tested by: Yiqing Yao <yiqing.yao@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Yiqing Yao <yiqing.yao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -3972,10 +3972,6 @@ void amdgpu_device_fini_hw(struct amdgpu_device *adev)
 {
 	dev_info(adev->dev, "amdgpu: finishing device.\n");
 	flush_delayed_work(&adev->delayed_init_work);
-	if (adev->mman.initialized) {
-		flush_delayed_work(&adev->mman.bdev.wq);
-		ttm_bo_lock_delayed_workqueue(&adev->mman.bdev);
-	}
 	adev->shutdown = true;
 
 	/* make sure IB test finished before entering exclusive mode
@@ -3996,6 +3992,11 @@ void amdgpu_device_fini_hw(struct amdgpu_device *adev)
 	}
 	amdgpu_fence_driver_hw_fini(adev);
 
+	if (adev->mman.initialized) {
+		flush_delayed_work(&adev->mman.bdev.wq);
+		ttm_bo_lock_delayed_workqueue(&adev->mman.bdev);
+	}
+
 	if (adev->pm_sysfs_en)
 		amdgpu_pm_sysfs_fini(adev);
 	if (adev->ucode_sysfs_en)