i40e: Fix ATR queue selection

Without this patch, ATR does not work. Receive/transmit uses queue
selection based on SW DCB hashing method.

If traffic classes are not configured for PF, then use
netdev_pick_tx function for selecting queue for packet transmission.
Instead of calling i40e_swdcb_skb_tx_hash, call netdev_pick_tx,
which ensures that packet is transmitted/received from CPU that is
running the application.

Reproduction steps:
1. Load i40e driver
2. Map each MSI interrupt of i40e port for each CPU
3. Disable ntuple, enable ATR i.e.:
ethtool -K $interface ntuple off
ethtool --set-priv-flags $interface flow-director-atr
4. Run application that is generating traffic and is bound to a
single CPU, i.e.:
taskset -c 9 netperf -H 1.1.1.1 -t TCP_RR -l 10
5. Observe behavior:
Application's traffic should be restricted to the CPU provided in
taskset.

Fixes: 89ec1f0 ("i40e: Fix queue-to-TC mapping on Tx")
Signed-off-by: Przemyslaw Patynowski <[email protected]>
Signed-off-by: Arkadiusz Kubalewski <[email protected]>
Tested-by: Dave Switzer <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kubalewski

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -3663,8 +3663,7 @@ u16 i40e_lan_select_queue(struct net_device *netdev,
 
 	/* is DCB enabled at all? */
 	if (vsi->tc_config.numtc == 1)
-		return i40e_swdcb_skb_tx_hash(netdev, skb,
-					      netdev->real_num_tx_queues);
+		return netdev_pick_tx(netdev, skb, sb_dev);
 
 	prio = skb->priority;
 	hw = &vsi->back->hw;