igb: Fix position of assignment to *ring

Assignment to *ring should be done after correctness check of the
argument queue.

Fixes: 91db3642 ("igb: Refactor igb_configure_cbs()")
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -1685,14 +1685,15 @@ static bool is_any_txtime_enabled(struct igb_adapter *adapter)
  **/
 static void igb_config_tx_modes(struct igb_adapter *adapter, int queue)
 {
-	struct igb_ring *ring = adapter->tx_ring[queue];
 	struct net_device *netdev = adapter->netdev;
 	struct e1000_hw *hw = &adapter->hw;
+	struct igb_ring *ring;
 	u32 tqavcc, tqavctrl;
 	u16 value;
 
 	WARN_ON(hw->mac.type != e1000_i210);
 	WARN_ON(queue < 0 || queue > 1);
+	ring = adapter->tx_ring[queue];
 
 	/* If any of the Qav features is enabled, configure queues as SR and
 	 * with HIGH PRIO. If none is, then configure them with LOW PRIO and