net: b44: replace dev_kfree_skb_xxx by dev_consume_skb_xxx for drop profiles

The skb should be freed by dev_consume_skb_any() in b44_start_xmit()
when bounce_skb is used. The skb is be replaced by bounce_skb, so the
original skb should be consumed(not drop).

dev_consume_skb_irq() should be called in b44_tx() when skb xmit
done. It makes drop profiles(dropwatch, perf) more friendly.

Signed-off-by: Yang Wei <yang.wei9@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>