drm/amd/display: Disable virtual links

[Why]
This could work around the issue with DP tunneling producing
a NULL pointer dereference.

[How]
Disable the virtual links.
Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Stylon Wang <stylon.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1713,7 +1713,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 
 	/* Enable DWB for tested platforms only */
 	if (adev->ip_versions[DCE_HWIP][0] >= IP_VERSION(3, 0, 0))
-		init_data.num_virtual_links = 1;
+		init_data.num_virtual_links = 0;
 
 	INIT_LIST_HEAD(&adev->dm.da_list);