e1000: add queue restart counter

Add a netif_wake/start_queue counter to the ethtool statistics to indicated
to the user that their transmit ring could be too small for their workload.

Signed-off-by: Jesse brandeburg <jesse.brandeburg@intel.com>
Cc: Jamal Hadi <hadi@cyberus.ca>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
diff --git a/drivers/net/e1000/e1000.h b/drivers/net/e1000/e1000.h
index 3f0be02..896ea8a 100644
--- a/drivers/net/e1000/e1000.h
+++ b/drivers/net/e1000/e1000.h
@@ -265,6 +265,7 @@
 
 	/* TX */
 	struct e1000_tx_ring *tx_ring;      /* One per active queue */
+	unsigned int restart_queue;
 	unsigned long tx_queue_len;
 	uint32_t txd_cmd;
 	uint32_t tx_int_delay;