be2net: Delete secondary unicast MAC addresses during be_close

Secondary unicast MAC addresses will get deleted only when the interface is UP.
When the interface is DOWN, though these secondary MAC addresses are unusable
and awaiting to be deleted, cause the firmware to believe that they are being used.
If the user intends to set a MAC address as primary MAC from one of these
secondary MAC addresses, the firmware returns a MAC address Collision error.
Delete these secondary MAC addresses during be_close.

The secondary MAC addresses list will be refreshed during interface open anyway.

Signed-off-by: Ajit Khaparde <ajit.khaparde@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>