netfilter: nftables: move nft_expr before nft_set

Move the nft_expr structure definition before nft_set. Expressions are
used by rules and sets, remove unnecessary forward declarations. This
comes as preparation to support for multiple expressions per set element.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables.h

@@ -305,8 +305,33 @@ struct nft_set_estimate {
 	enum nft_set_class	space;
 };
 
+#define NFT_EXPR_MAXATTR		16
+#define NFT_EXPR_SIZE(size)		(sizeof(struct nft_expr) + \
+					 ALIGN(size, __alignof__(struct nft_expr)))
+
+/**
+ *	struct nft_expr - nf_tables expression
+ *
+ *	@ops: expression ops
+ *	@data: expression private data
+ */
+struct nft_expr {
+	const struct nft_expr_ops	*ops;
+	unsigned char			data[]
+		__attribute__((aligned(__alignof__(u64))));
+};
+
+static inline void *nft_expr_priv(const struct nft_expr *expr)
+{
+	return (void *)expr->data;
+}
+
+int nft_expr_clone(struct nft_expr *dst, struct nft_expr *src);
+void nft_expr_destroy(const struct nft_ctx *ctx, struct nft_expr *expr);
+int nft_expr_dump(struct sk_buff *skb, unsigned int attr,
+		  const struct nft_expr *expr);
+
 struct nft_set_ext;
-struct nft_expr;
 
 /**
  *	struct nft_set_ops - nf_tables set operations
@@ -797,7 +822,6 @@ struct nft_offload_ctx;
  *	@validate: validate expression, called during loop detection
  *	@data: extra data to attach to this expression operation
  */
-struct nft_expr;
 struct nft_expr_ops {
 	void				(*eval)(const struct nft_expr *expr,
 						struct nft_regs *regs,
@@ -833,32 +857,6 @@ struct nft_expr_ops {
 	void				*data;
 };
 
-#define NFT_EXPR_MAXATTR		16
-#define NFT_EXPR_SIZE(size)		(sizeof(struct nft_expr) + \
-					 ALIGN(size, __alignof__(struct nft_expr)))
-
-/**
- *	struct nft_expr - nf_tables expression
- *
- *	@ops: expression ops
- *	@data: expression private data
- */
-struct nft_expr {
-	const struct nft_expr_ops	*ops;
-	unsigned char			data[]
-		__attribute__((aligned(__alignof__(u64))));
-};
-
-static inline void *nft_expr_priv(const struct nft_expr *expr)
-{
-	return (void *)expr->data;
-}
-
-int nft_expr_clone(struct nft_expr *dst, struct nft_expr *src);
-void nft_expr_destroy(const struct nft_ctx *ctx, struct nft_expr *expr);
-int nft_expr_dump(struct sk_buff *skb, unsigned int attr,
-		  const struct nft_expr *expr);
-
 /**
  *	struct nft_rule - nf_tables rule
  *