igb: change how we handle alternate mac addresses

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>
diff --git a/drivers/net/igb/e1000_82575.c b/drivers/net/igb/e1000_82575.c
index e07f66c..45063c2 100644
--- a/drivers/net/igb/e1000_82575.c
+++ b/drivers/net/igb/e1000_82575.c
@@ -1152,9 +1152,18 @@
 {
 	s32 ret_val = 0;
 
-	if (igb_check_alt_mac_addr(hw))
-		ret_val = igb_read_mac_addr(hw);
+	/*
+	 * If there's an alternate MAC address place it in RAR0
+	 * so that it will override the Si installed default perm
+	 * address.
+	 */
+	ret_val = igb_check_alt_mac_addr(hw);
+	if (ret_val)
+		goto out;
 
+	ret_val = igb_read_mac_addr(hw);
+
+out:
 	return ret_val;
 }