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

Delete a redundant comment line in lmc_interrupt().
Signed-off-by: Yang Wei <yang.wei9@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>