netfilter: nft_set_pipapo_avx2: remove redundant pointer lt

The pointer lt is being assigned a value and then later
updated but that value is never read. The pointer is
redundant and can be removed.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>