switchdev: add support for fdb add/del/dump via switchdev_port_obj ops.

- introduce port fdb obj and generic switchdev_port_fdb_add/del/dump()
- use switchdev_port_fdb_add/del/dump in rocker/team/bonding ndo ops.
- add support for fdb obj in switchdev_port_obj_add/del/dump()
- switch rocker to implement fdb ops via switchdev_ops

v3: updated to sync with named union changes.

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>