net: caif: call dev_consume_skb_any when skb xmit done

The skb shouled be consumed when xmit done, it makes drop profiles
(dropwatch, perf) more friendly.
dev_kfree_skb_irq()/kfree_skb() shouled be replaced by
dev_consume_skb_any(), it makes code cleaner.
Signed-off-by: Yang Wei <yang.wei9@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/caif/caif_serial.c

@@ -257,10 +257,7 @@ static int handle_tx(struct ser_device *ser)
 		if (skb->len == 0) {
 			struct sk_buff *tmp = skb_dequeue(&ser->head);
 			WARN_ON(tmp != skb);
-			if (in_interrupt())
-				dev_kfree_skb_irq(skb);
-			else
-				kfree_skb(skb);
+			dev_consume_skb_any(skb);
 		}
 	}
 	/* Send flow off if queue is empty */