It is needed to track correct Tx topology. Update it every time new
representor is created or remove node in case of removing corresponding
representor.

Still clear all node when removing switchdev mode as part of Tx topology
isn't related only to representors. Also clear ::rate_note value to
prevent skipping this node next time Tx topology is created.
Reviewed-by: Piotr Raczynski <piotr.raczynski@intel.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>