Allow reprogramming of the RAR with a zero mac address,
to ensure that the VF traffic goes to the PF after
stop, close and detach of the VF.
Fixes: be2d648a2d ("igb: add PF support")
Fixes: d82170d279 ("igb: add VF support")
Signed-off-by: Bernard Iremonger <bernard.iremonger@intel.com>
Acked-by: Wenzhuo Lu <wenzhuo.lu@intel.com>