drm/amdgpu: add vram_info v3_0 structure

To support query vram_width, vram_type, vram_vendor
information

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Likun Gao <Likun.Gao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>