igb: fix error code in igb_add_ethtool_nfc_entry()

Use error "rmgr: Cannot insert RX class rule: Operation not supported" is
more meaningful than "rmgr: Cannot insert RX class rule: Unknown error 524"

Signed-off-by: Gangfeng Huang <gangfeng.huang@ni.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/igb_ethtool.c

@@ -2851,7 +2851,7 @@ static int igb_add_ethtool_nfc_entry(struct igb_adapter *adapter,
 	int err = 0;
 
 	if (!(netdev->hw_features & NETIF_F_NTUPLE))
-		return -ENOTSUPP;
+		return -EOPNOTSUPP;
 
 	/* Don't allow programming if the action is a queue greater than
 	 * the number of online Rx queues.