Replace dev_kfree_skb with dev_consume_skb_any in el3_start_xmit
as it can be called in hard irq and other contexts.

dev_consume_skb_any is used as on this simple hardware the
skb is consumed directly by the start_xmit function.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>