drm/amdgpu: increase gart size to 512MB

256MB is too small consider PTE/PDE shadow and TTM
eviction activity

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
1 file changed