netfilter: nf_tables: don't initialize registers in nft_do_chain()

revert commit 4c905f67 ("netfilter: nf_tables: initialize registers in
nft_do_chain()").

Previous patch makes sure that loads from uninitialized registers are
detected from the control plane. in this case rule blob auto-zeroes
registers.  Thus the explicit zeroing is not needed anymore.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_core.c

@@ -256,7 +256,7 @@ nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 	const struct net *net = nft_net(pkt);
 	const struct nft_expr *expr, *last;
 	const struct nft_rule_dp *rule;
-	struct nft_regs regs = {};
+	struct nft_regs regs;
 	unsigned int stackptr = 0;
 	struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 	bool genbit = READ_ONCE(net->nft.gencursor);