In libertas_process_rxed_packet() and process_rxed_802_11_packet() the
skb is dereferenced after being passed to netif_rx (called from
libertas_upload_rx_packet). Spotted by Coverity (1658, 1659).

Also, libertas_upload_rx_packet() unconditionally returns 0 so the error
check is dead code - might as well take it out and change the signature.
Signed-off-by: Florin Malita <fmalita@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>