netfilter: nf_tables: move base hook annotation to init helper

coverity scanner says:
2187  if (nft_is_base_chain(chain)) {
vvv   CID 1505166:  Memory - corruptions  (UNINIT)
vvv   Using uninitialized value "basechain".
2188  basechain->ops.hook_ops_type = NF_HOOK_OP_NF_TABLES;

... I don't see how nft_is_base_chain() can evaluate to true
while basechain pointer is garbage.

However, it seems better to place the NF_HOOK_OP_NF_TABLES annotation
in nft_basechain_hook_init() instead.
Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1505166 ("Memory - corruptions")
Fixes: 65b8b7bfc5284f ("netfilter: annotate nf_tables base hook ops")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -2002,6 +2002,7 @@ static void nft_basechain_hook_init(struct nf_hook_ops *ops, u8 family,
 	ops->priority		= hook->priority;
 	ops->priv		= chain;
 	ops->hook		= hook->type->hooks[ops->hooknum];
+	ops->hook_ops_type	= NF_HOOK_OP_NF_TABLES;
 }
 
 static int nft_basechain_init(struct nft_base_chain *basechain, u8 family,
@@ -2168,10 +2169,8 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 	}
 
 	nft_trans_chain_policy(trans) = NFT_CHAIN_POLICY_UNSET;
-	if (nft_is_base_chain(chain)) {
-		basechain->ops.hook_ops_type = NF_HOOK_OP_NF_TABLES;
+	if (nft_is_base_chain(chain))
 		nft_trans_chain_policy(trans) = policy;
-	}
 
 	err = nft_chain_add(table, chain);
 	if (err < 0) {