netfilter: x_tables: unbreak module auto loading

a typo causes module auto load support to never be compiled in.

Fixes: 03d13b68 ("netfilter: xtables: add and use xt_request_find_table_lock")
Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>