Replace dev_kfree_skb with dev_kfree_skb_any in mtk_start_xmit()
which can be called from hard irq context (netpoll) and from
other contexts. mtk_start_xmit() only frees skbs that it has
dropped.

This is detected by Coccinelle semantic patch.
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>