netfilter: nf_tables: fix ifdef to also consider nf_tables=m

nftables can be built as a module, so fix the preprocessor conditional
accordingly.

Fixes: 478b360 ("netfilter: nf_tables: fix nf_trace always-on with XT_TRACE=n")
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Author: Florian Westphal

include/linux/skbuff.h

@@ -4713,7 +4713,7 @@ static inline void nf_reset_ct(struct sk_buff *skb)
 
 static inline void nf_reset_trace(struct sk_buff *skb)
 {
-#if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
+#if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || IS_ENABLED(CONFIG_NF_TABLES)
 	skb->nf_trace = 0;
 #endif
 }
@@ -4733,7 +4733,7 @@ static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
 	dst->_nfct = src->_nfct;
 	nf_conntrack_get(skb_nfct(src));
 #endif
-#if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
+#if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || IS_ENABLED(CONFIG_NF_TABLES)
 	if (copy)
 		dst->nf_trace = src->nf_trace;
 #endif