rtl8169_tx_interrupt() is used from NAPI context, it can
directly free skbs. dev_kfree_skb_irq() is a leftover from
pre-NAPI times of this driver.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>