netfilter: nf_tables: add nft_is_base_chain() helper

This new helper function allows us to check if this is a basechain.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables.h

@@ -911,6 +911,11 @@ static inline struct nft_base_chain *nft_base_chain(const struct nft_chain *chai
 	return container_of(chain, struct nft_base_chain, chain);
 }
 
+static inline bool nft_is_base_chain(const struct nft_chain *chain)
+{
+	return chain->flags & NFT_BASE_CHAIN;
+}
+
 int __nft_release_basechain(struct nft_ctx *ctx);
 
 unsigned int nft_do_chain(struct nft_pktinfo *pkt, void *priv);