The skb is needed only to fetch the keys for the lookup.

Both functions are used from GRO stack, we do not want
accidental modification of the skb.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NAlexander Lobakin <alobakin@pm.me>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>