igb: Force flow control off during reset when forcing speed.

During igb_reset(), we initiate a hardware reset which will clear our
flow control settings. For auto-negotiation, we re-negotiate them when
linking up again, but we need to force them off properly for the forced
speed case.
Signed-off-by: Matthew Vick <matthew.vick@intel.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_main.c

@@ -1715,6 +1715,13 @@ void igb_reset(struct igb_adapter *adapter)
 	if (hw->mac.ops.init_hw(hw))
 		dev_err(&pdev->dev, "Hardware Error\n");
 
+	/*
+	 * Flow control settings reset on hardware reset, so guarantee flow
+	 * control is off when forcing speed.
+	 */
+	if (!hw->mac.autoneg)
+		igb_force_mac_fc(hw);
+
 	igb_init_dmac(adapter, pba);
 	if (!netif_running(adapter->netdev))
 		igb_power_down_link(adapter);