rule: fix netlink debug flag when listing table/rules

rule: fix netlink debug flag when listing table/rules

nft --debug=netlink list table ...
has no effect anymore.

Callers pass in debug_mask & DEBUG_NETLINK, which gets converted
to 0/1 because the arg is a boolean.

Later on this bool is converted back to an integer, but that
won't have the desired result.

Fixes: be441e1ffdc24 ("src: add debugging mask to context structure")
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>