drm/amdkfd: replace source_id with client_id for RAS poison consumption

Client ID is more accruate here and we can deal with more different
cases with client ID.

Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>