enic: Flush driver cache of registered addr lists during port profile disassociate

During a port profile disassociate all address registrations for the interface
are blown away from the adapter. This patch resets the driver cache of
registered address lists to zero after a port profile disassociate.

Signed-off-by: Roopa Prabhu <roprabhu@cisco.com>
Signed-off-by: David Wang <dwang2@cisco.com>
Signed-off-by: Christian Benvenuti <benve@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>