nfp: flower: ensure MAC cleanup on address change

It is possible to receive a MAC address change notification without the
net device being down (e.g. when an OvS bridge is assigned the same MAC as
a port added to it). This means that an offloaded MAC address may not be
removed if its device gets a new address.

Maintain a record of the offloaded MAC addresses for each repr and netdev
assigned a MAC offload index. Use this to delete the (now expired) MAC if
a change of address event occurs. Only handle change address events if the
device is already up - if not then the netdev up event will handle it.

Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>