netfilter: revert nft_set_rbtree: validate open interval overlap

netfilter: revert nft_set_rbtree: validate open interval overlap

This reverts commit 648946966a08 ("netfilter: nft_set_rbtree: validate
open interval overlap").

There have been reports of nft failing to laod valid rulesets after this
patch was merged into -stable.

I can reproduce several such problem with recent nft versions, including
nft 1.1.6 which is widely shipped by distributions.

We currently have little choice here.
This commit can be resurrected at some point once the nftables fix that
triggers the false overlap positive has appeared in common distros
(see e83e32c8d1cd ("mnl: restore create element command with large batches" in
 nftables.git).

Fixes: 648946966a08 ("netfilter: nft_set_rbtree: validate open interval overlap")
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>