i40e: Skip the priority tagging if DCB is not enabled

If DCB is not enabled priority tagging is not needed
so skip over that section.

Change-ID: Ia3f3fa07945b421259a9ca38329d6d1cbd6c6bcc
Signed-off-by: NNeerav Parikh <neerav.parikh@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -2043,6 +2043,9 @@ static int i40e_tx_prepare_vlan_flags(struct sk_buff *skb,
 		tx_flags |= I40E_TX_FLAGS_SW_VLAN;
 	}
 
+	if (!(tx_ring->vsi->back->flags & I40E_FLAG_DCB_ENABLED))
+		goto out;
+
 	/* Insert 802.1p priority into VLAN header */
 	if ((tx_flags & (I40E_TX_FLAGS_HW_VLAN | I40E_TX_FLAGS_SW_VLAN)) ||
 	    (skb->priority != TC_PRIO_CONTROL)) {
@@ -2063,6 +2066,8 @@ static int i40e_tx_prepare_vlan_flags(struct sk_buff *skb,
 			tx_flags |= I40E_TX_FLAGS_HW_VLAN;
 		}
 	}
+
+out:
 	*flags = tx_flags;
 	return 0;
 }