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>