Turned out the commit is incomplete and since we remove using the AGP
mapping from the GTT manager it is also not necessary any more.

This reverts commit 22d8bfaf.
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: James Zhu <James.Zhu@amd.com>
Tested-by: James Zhu <James.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>