net: pch_gbe: fix potential memleak in pch_gbe_tx_queue()

In pch_gbe_xmit_frame(), NETDEV_TX_OK will be returned whether
pch_gbe_tx_queue() sends data successfully or not, so pch_gbe_tx_queue()
needs to free skb before returning. But pch_gbe_tx_queue() returns without
freeing skb in case of dma_map_single() fails. Add dev_kfree_skb_any()
to fix it.

Fixes: 77555ee7 ("net: Add Gigabit Ethernet driver of Topcliff PCH")
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>