drivers/ethernet: Remove double unref from stellaris driver

It's now either L2 which unref the pkt on successful tx, or net_if on
error.

Also removing pkt->frags check, net_core.c:net_send_data() does it
already.

And using data_len in logging instead of net_pkt_get_len(), which one is
currently greedy (it goes over all net_bufs).

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
1 file changed