switchdev: add new switchdev_port_bridge_dellink

Same change as setlink.  Provide the wrapper op for SELF ndo_bridge_dellink
and call into the switchdev driver to delete afspec VLANs.

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