igb: Alternate MAC Address EEPROM Updates

This code check word 0x37 in the EEPROM, if it is 0xFFFF _or_ 0x0000, then
there is no Alternate MAC Address in the EEPROM.
Signed-off-by: "Akeem G. Abodunrin" <akeem.g.abodunrin@intel.com>
Tested-by: Aaron Brown  <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/e1000_mac.c

@@ -198,10 +198,10 @@ s32 igb_check_alt_mac_addr(struct e1000_hw *hw)
 		goto out;
 	}
 
-	if (nvm_alt_mac_addr_offset == 0xFFFF) {
+	if ((nvm_alt_mac_addr_offset == 0xFFFF) ||
+	    (nvm_alt_mac_addr_offset == 0x0000))
 		/* There is no Alternate MAC Address */
 		goto out;
-	}
 
 	if (hw->bus.func == E1000_FUNC_1)
 		nvm_alt_mac_addr_offset += E1000_ALT_MAC_ADDRESS_OFFSET_LAN1;