3672 mac_unregister does not clear mi_dstaddr_set
Reviewed by: Carlos Cardenas <carlos.cardenas@joyent.com>
Reviewed by: Dan McDonald <danmcd@nexenta.com>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Approved by: Dan McDonald <danmcd@nexenta.com>