netfilter: nf_tables: correct NFT_LOGLEVEL_MAX value

should be same as NFT_LOGLEVEL_AUDIT, so use -, not +.

Fixes: 7eced5ab ("netfilter: nf_tables: add NFT_LOGLEVEL_* enumeration and use it")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/nf_tables.h

@@ -1134,7 +1134,7 @@ enum nft_log_level {
 	NFT_LOGLEVEL_AUDIT,
 	__NFT_LOGLEVEL_MAX
 };
-#define NFT_LOGLEVEL_MAX	(__NFT_LOGLEVEL_MAX + 1)
+#define NFT_LOGLEVEL_MAX	(__NFT_LOGLEVEL_MAX - 1)
 
 /**
  * enum nft_queue_attributes - nf_tables queue expression netlink attributes