mv643xx_eth: Call dev_kfree_skb_any instead of dev_kfree_skb.

Replace dev_kfree_skb with dev_kfree_skb_any in mv643xx_eth_xmit and
txq_submit_skb that can be called in hard irq and other contexts,
on paths where the skbs are dropped.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>