drm/amdgpu: add RAVEN pci id (v2)

Add the RAVEN pci id.

v2: add exp flag for now (Alex)

Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>