PCI GART doesn't support unsnooped access. AGP GART already uses
write-combined CPU mappings.
Signed-off-by: NMichel Dänzer <michel.daenzer@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>