drm/amdgpu: put GART away from VRAM v2

Always try to put the GART away from where VRAM is.

v2: correctly handle the 4GB limitation

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
1 file changed