drm/amdgpu: support get_vram_info atomfirmware i/f for aldebaran

Query vram_type, channel_num, channel_width
information through atomfirmware i/f

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