sky2: keep track of receive alloc failures

When driver can't allocate receive buffer it drops incoming
packet. Keep a counter.
Signed-off-by: NStephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/net/sky2.c

@@ -2141,8 +2141,10 @@ static int sky2_status_intr(struct sky2_hw *hw, int to_do)
 		switch (le->opcode & ~HW_OWNER) {
 		case OP_RXSTAT:
 			skb = sky2_receive(dev, length, status);
-			if (!skb)
+			if (unlikely(!skb)) {
+				sky2->net_stats.rx_dropped++;
 				goto force_update;
+			}
 
 			skb->protocol = eth_type_trans(skb, dev);
 			sky2->net_stats.rx_packets++;