platform: don't listen for tc netlink messages
Update nm_platform_qdisc_sync() and nm_platform_tfilter_sync() to avoid looking into the platform cache, so that we no longer require to keep tc and qdiscs in the cache.
There is no API in kernel to retrieve tc objects only for a specific interface, so NM had to receive all tc events, even for unmanaged interfaces. This could cause high CPU usage in some scenarios with any objects.