e1000: omit stats for broken counter in 82543

The 82543 chip does not count tx_carrier_errors properly in FD mode;
report zeros instead of garbage.

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_hw.c b/drivers/net/e1000/e1000_hw.c
index 0201ca5..ce82eb5 100644
--- a/drivers/net/e1000/e1000_hw.c
+++ b/drivers/net/e1000/e1000_hw.c
@@ -442,6 +442,12 @@
 		break;
 	}
 
+	/* The 82543 chip does not count tx_carrier_errors properly in
+	 * FD mode
+	 */
+	if (hw->mac_type == e1000_82543)
+		hw->bad_tx_carr_stats_fd = TRUE;
+
 	return E1000_SUCCESS;
 }