igb: Enable auto-crossover during forced operation on 82580 and above.

Newer devices supported by igb can support auto-crossover detection in
forced operation modes. Enable this in the driver, rather than clobbering
this functionality in forced operation.

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>
diff --git a/drivers/net/ethernet/intel/igb/e1000_mac.c b/drivers/net/ethernet/intel/igb/e1000_mac.c
index 819c145..7acddfe 100644
--- a/drivers/net/ethernet/intel/igb/e1000_mac.c
+++ b/drivers/net/ethernet/intel/igb/e1000_mac.c
@@ -1391,6 +1391,10 @@
 {
 	s32 ret_val = 0;
 
+	/* All MDI settings are supported on 82580 and newer. */
+	if (hw->mac.type >= e1000_82580)
+		goto out;
+
 	if (!hw->mac.autoneg && (hw->phy.mdix == 0 || hw->phy.mdix == 3)) {
 		hw_dbg("Invalid MDI setting detected\n");
 		hw->phy.mdix = 1;