Revert "drm/amdgpu: install stub fence into potential unused fence pointers"

This reverts commit 4921792e which is
commit 187916e6 upstream.

It is reported to cause a lot of log spam, so should be reverted.

Link: https://lore.kernel.org/r/d32d6919-47cf-4ddc-955a-0759088220ae@gmail.com
Link: https://lore.kernel.org/r/BL1PR12MB5144A0E84378A2666A26AE18F7F2A@BL1PR12MB5144.namprd12.prod.outlook.com


Reported-by: Bryan Jennings <bryjen423@gmail.com>
Reported-by: Alexander Deucher <Alexander.Deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Lang Yu <Lang.Yu@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>