If use gart for FB translation, allocate and fill
PDB0.
Signed-off-by: NOak Zeng <Oak.Zeng@amd.com>
Reviewed-by: NChristian Konig <christian.koenig@amd.com>
Reviewed-by: NFelix Kuehling <felix.kuehling@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>