netfilter: nfnetlink_queue: fix incorrect initialization of copy range field

2^16 = 0xffff, not 0xfffff (note the extra 'f'). Not dangerous since you
adjust it to min_t(data_len, skb->len) just after on.

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>