xdp: add tracepoint for devmap like cpumap have

Notice how this allow us get XDP statistic without affecting the XDP
performance, as tracepoint is no-longer activated on a per packet basis.

V5: Spotted by John Fastabend.
 Fix 'sent' also counted 'drops' in this patch, a later patch corrected
 this, but it was a mistake in this intermediate step.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net/core/filter.c

@@ -3067,7 +3067,7 @@ static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
 	case BPF_MAP_TYPE_DEVMAP: {
 		struct bpf_dtab_netdev *dst = fwd;
 
-		err = dev_map_enqueue(dst, xdp);
+		err = dev_map_enqueue(dst, xdp, dev_rx);
 		if (err)
 			return err;
 		__dev_map_insert_ctx(map, index);