Querying PCI Device in NCCL macOS 2.9.6

As in original implementation of NCCL, the author queries device status via going through files under device folder /sys/. However, for macOS PCI device status (NVLink device can't be supported by macOS) should be learnt via I/O Kit. To be specific, we need to resort toDevice Access and the I/O Kit.

Therefore, topo.cc has been migrated to implementation via I/O Kit.