igb: change how we handle alternate mac addresses

igb: change how we handle alternate mac addresses

commit 22896639af98ebc721a94ed71fc3acf2fb4a24dc upstream.

This patch allows us to treat the alternate mac address as though it is the
physical address on the adapter.  This is accomplished by letting the
alt_mac_address function to only fail on an NVM error.  If no errors occur
and the alternate mac address is not present then RAR0 is read as the
default mac address.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Brandon Philips <bphilips@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>