netfilter: nft_log: request explicit logger when loading rules

This includes the special handling for NFPROTO_INET. There is
no real inet logger since we don't see packets of this family.
However, rules are loaded using this special family type. So
let's just request both IPV4 and IPV6 loggers.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>