s2io: Call dev_kfree_skb_any instead of dev_kfree_skb.

Replace dev_kfree_skb with dev_kfree_skb_any in s2io_xmit that can
be called in hard irq and other contexts.

All instances that are changed are packet drops.

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