[NET]: In sock_queue_rcv_skb(), do not deref skb->len after it is queued to the socket.

[NET]: In sock_queue_rcv_skb(), do not deref skb->len after it is queued to the socket.

In implementations that use no socket locking, such as RAW sockets,
once we queue the SKB to the socket another cpu can remove the SKB
from the socket queue and free up the SKB making the skb->len access
touch freed memory.

Based upon a report from Burton Windle, kernel bugzilla #937