e1000: 3 new driver stats for managability testing

Add 3 extra packet redirect counters for tracking purposes to make sure
we can test that all packets arrive properly.

Originally from Jesse Brandeburg <jesse.brandeburg@intel.com>,
rewritten to use feature flags by me.

Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 3f40a90..b06b51a 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -3743,6 +3743,13 @@
 			adapter->phy_stats.receive_errors += phy_tmp;
 	}
 
+	/* Management Stats */
+	if (adapter->hw.has_smbus) {
+		adapter->stats.mgptc += E1000_READ_REG(hw, MGTPTC);
+		adapter->stats.mgprc += E1000_READ_REG(hw, MGTPRC);
+		adapter->stats.mgpdc += E1000_READ_REG(hw, MGTPDC);
+	}
+
 	spin_unlock_irqrestore(&adapter->stats_lock, flags);
 }
 #ifdef CONFIG_PCI_MSI