be2net: Fix change MAC operation for VF for Lancer

For changing MAC of VF from PF, delete MAC operation needs to be done before
assigning new MAC. Also in ndo_set_mac_address operation avoid delete MAC if
it has been already deleted by PF.

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>