hv_netvsc: track memory allocation failures in ethtool stats

When skb can not be allocated, update ethtool statisitics
rather than rx_dropped which is intended for netif_receive.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 845ddc7..ef8c9fb 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -705,6 +705,7 @@ struct netvsc_ethtool_stats {
 	unsigned long tx_busy;
 	unsigned long tx_send_full;
 	unsigned long rx_comp_busy;
+	unsigned long rx_no_memory;
 	unsigned long stop_queue;
 	unsigned long wake_queue;
 };