wireguard: receive: use dev_sw_netstats_rx_add()

We have a convenient helper, let's use it.
This will make the following patch easier to review and smaller.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/wireguard/receive.c

@@ -19,15 +19,8 @@
 /* Must be called with bh disabled. */
 static void update_rx_stats(struct wg_peer *peer, size_t len)
 {
-	struct pcpu_sw_netstats *tstats =
-		get_cpu_ptr(peer->device->dev->tstats);
-
-	u64_stats_update_begin(&tstats->syncp);
-	++tstats->rx_packets;
-	tstats->rx_bytes += len;
+	dev_sw_netstats_rx_add(peer->device->dev, len);
 	peer->rx_bytes += len;
-	u64_stats_update_end(&tstats->syncp);
-	put_cpu_ptr(tstats);
 }
 
 #define SKB_TYPE_LE32(skb) (((struct message_header *)(skb)->data)->type)