Otherwise, if nfnetlink_log.ko is not loaded, we cannot add rules
to log packets to the userspace when we specify it with arp family,
such as:

  # nft add rule arp filter input log group 0
  <cmdline>:1:1-37: Error: Could not process rule: No such file or
  directory
  add rule arp filter input log group 0
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>