drm/amd/amdgpu: move drain_workqueue before shutdown is set

[background] when unloading amdgpu driver right after running a
workload, drain_workqueue is causing "Fence fallback timer
expired on ring sdma0.0". Under sriov, this issue will cause sriov
full access timeout and a reset happening.

move drain_workqueue before shutdown is set to allow ih process and
before enter full access under sriov to avoid full access time cost.
Signed-off-by: Victor Zhao <Victor.Zhao@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -4531,6 +4531,9 @@ 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)
+		drain_workqueue(adev->mman.bdev.wq);
 	adev->shutdown = true;
 
 	/* make sure IB test finished before entering exclusive mode
@@ -4551,9 +4554,6 @@ void amdgpu_device_fini_hw(struct amdgpu_device *adev)
 	}
 	amdgpu_fence_driver_hw_fini(adev);
 
-	if (adev->mman.initialized)
-		drain_workqueue(adev->mman.bdev.wq);
-
 	if (adev->pm.sysfs_initialized)
 		amdgpu_pm_sysfs_fini(adev);
 	if (adev->ucode_sysfs_en)