netfilter: nft_bitwise: fix register tracking

At the end of `nft_bitwise_reduce`, there is a loop which is intended to
update the bitwise expression associated with each tracked destination
register.  However, currently, it just updates the first register
repeatedly.  Fix it.

Fixes: 34cc9e52 ("netfilter: nf_tables: cancel tracking for clobbered destination registers")
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_bitwise.c

@@ -323,7 +323,7 @@ static bool nft_bitwise_reduce(struct nft_regs_track *track,
 	dreg = priv->dreg;
 	regcount = DIV_ROUND_UP(priv->len, NFT_REG32_SIZE);
 	for (i = 0; i < regcount; i++, dreg++)
-		track->regs[priv->dreg].bitwise = expr;
+		track->regs[dreg].bitwise = expr;
 
 	return false;
 }