drm/amdgpu: preserve the num_links in case of reflection

For topology reflection, each socket to every other socket has the
exactly same topology info as the other way around. So it is safe
to keep the reflected num_links value otherwise it will be overriden
by the link info output of GET_PEER_LINKS command.

Signed-off-by: Shiwu Zhang <shiwu.zhang@amd.com>
Reviewed-by: Le Ma <le.ma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>