net/sched: Introduce tc block netdev tracking infra

net/sched: Introduce tc block netdev tracking infra

This commit makes tc blocks track which ports have been added to them.
And, with that, we'll be able to use this new information to send
packets to the block's ports. Which will be done in the patch #3 of this
series.

Suggested-by: Jiri Pirko <[email protected]>
Co-developed-by: Jamal Hadi Salim <[email protected]>
Signed-off-by: Jamal Hadi Salim <[email protected]>
Co-developed-by: Pedro Tammela <[email protected]>
Signed-off-by: Pedro Tammela <[email protected]>
Signed-off-by: Victor Nogueira <[email protected]>
Signed-off-by: David S. Miller <[email protected]>