rocker: store rocker_port in fdb key rather than pport

We'll need more info from rocker_port than just pport when we age out fdb
entries, so store rocker_port rather than pport in each fdb entry.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>