igb: read PBA number from flash

Fixed flash presence check for 82576 controllers so the part
number string is read and displayed correctly.
Signed-off-by: Gal Hammer <ghammer@redhat.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -3532,7 +3532,9 @@ static int igb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 			  "Width x1" : "unknown"), netdev->dev_addr);
 	}
 
-	if ((hw->mac.type >= e1000_i210 ||
+	if ((hw->mac.type == e1000_82576 &&
+	     rd32(E1000_EECD) & E1000_EECD_PRES) ||
+	    (hw->mac.type >= e1000_i210 ||
 	     igb_get_flash_presence_i210(hw))) {
 		ret_val = igb_read_part_string(hw, part_str,
 					       E1000_PBANUM_LENGTH);