bpf: no need to nullify ri->map in xdp_do_redirect

We are guaranteed to have a NULL ri->map in this branch since
we test for it earlier, so we don't need to reset it here.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/filter.c

@@ -2568,7 +2568,6 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 
 	fwd = dev_get_by_index_rcu(dev_net(dev), index);
 	ri->ifindex = 0;
-	ri->map = NULL;
 	if (unlikely(!fwd)) {
 		bpf_warn_invalid_xdp_redirect(index);
 		return -EINVAL;