drm/amdkfd: Add device to topology after it is completely inited

We can't have devices that are not completely initialized in kfd topology.
Otherwise it is a race condition when user access not completely
initialized device. This also addresses a kfd_topology_add_device accessing
NULL dqm pointer issue.

Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>