drm/amdgpu: change amdgpu_ttm_set_active_vram_size

Instead of setting the active VRAM size directly provide a the info if
we can use the buffer functions or not.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Chunming zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
7 files changed