igb: Fix stats output on i210/i211 parts.

Due to a hardware issue, on i210 and i211 parts, the TNCRS statistic
provides an invalid value.  This patch changes the update stats function
to increment the stat only for non-i210/i211 parts.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -4776,7 +4776,11 @@ void igb_update_stats(struct igb_adapter *adapter,
 	reg = rd32(E1000_CTRL_EXT);
 	if (!(reg & E1000_CTRL_EXT_LINK_MODE_MASK)) {
 		adapter->stats.rxerrc += rd32(E1000_RXERRC);
-		adapter->stats.tncrs += rd32(E1000_TNCRS);
+
+		/* this stat has invalid values on i210/i211 */
+		if ((hw->mac.type != e1000_i210) &&
+		    (hw->mac.type != e1000_i211))
+			adapter->stats.tncrs += rd32(E1000_TNCRS);
 	}
 
 	adapter->stats.tsctc += rd32(E1000_TSCTC);