netfilter: xt_hashlimit: fix a possible memory leak in htable_create()

In the htable_create(), hinfo is allocated by vmalloc()
So that if error occurred, hinfo should be freed.

Fixes: 11d5f157 ("netfilter: xt_hashlimit: Create revision 2 to support higher pps rates")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>