netfilter: ipset: Fix oversized kvmalloc() calls

The commit

commit 7661809d


Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed Jul 14 09:45:49 2021 -0700

    mm: don't allow oversized kvmalloc() calls

limits the max allocatable memory via kvmalloc() to MAX_INT. Apply the
same limit in ipset.

Reported-by:  <syzbot+3493b1873fb3ea827986@syzkaller.appspotmail.com>
Reported-by:  <syzbot+2b8443c35458a617c904@syzkaller.appspotmail.com>
Reported-by:  <syzbot+ee5cb15f4a0e85e0d54e@syzkaller.appspotmail.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>