netfilter: nf_fwd_netdev: clear timestamp in forwarding path

Similar to 7980d2eabde8 ("ipvs: clear skb->tstamp in forwarding path").
fq qdisc requires tstamp to be cleared in forwarding path.

Fixes: 8203e2d844d3 ("net: clear skb->tstamp in forwarding paths")
Fixes: fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC")
Fixes: 80b14dee2bea ("net: Add a new socket option for a future transmit time.")
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/nf_dup_netdev.c

···
 		skb_push(skb, skb->mac_len);
 
 	skb->dev = dev;
+	skb->tstamp = 0;
 	dev_queue_xmit(skb);
 }
 

net/netfilter/nft_fwd_netdev.c

···
 		return;
 
 	skb->dev = dev;
+	skb->tstamp = 0;
 	neigh_xmit(neigh_table, dev, addr, skb);
 out:
 	regs->verdict.code = verdict;