be2net: Fix mac address collision in some configurations

If the device mac address is updated using ndo_set_mac_address(),
while the same mac address is already programmed, the driver does not
detect this condition if its netdev->dev_addr has been changed. The
driver tries to add the same mac address resulting in mac address
collision error. This has been observed in bonding mode-5 configuration.

To fix this, store the mac address configured in HW in the adapter
structure. Use this to compare against the new address being updated
to avoid collision.

Signed-off-by: Suresh Reddy <Suresh.Reddy@broadcom.com>
Signed-off-by: Sathya Perla <sathya.perla@broadcom.com>
Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>