netfilter: nf_tables: correct NFT_LOGLEVEL_MAX value

mainline inclusion
from mainline-5.2-rc1
commit 92285a07
category: bugfix
bugzilla: 15923
CVE: NA

-------------------------------------------------

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: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

include/uapi/linux/netfilter/nf_tables.h

@@ -1128,7 +1128,7 @@ 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