drm/amdgpu: add CHIP_IP_DISCOVERY support for virtualization

For further chips we will use CHIP_IP_DISCOVERY, so add this
support for virtualization

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Horace Chen <horace.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>