net: fix typo in freescale/ucc_geth.c

The following patch:
  acb600de net: remove skb recycling
added dev_free_skb() to drivers/net/ethernet/freescale/ucc_geth.c

This is a typo and should be dev_kfree_skb().  This fixes this.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: David S. Miller <davem@davemloft.net>