ppp: avoid false drop_monitor false positives

Call consume_skb() in place of kfree_skb() were appropriate.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c
index dd15b8f..cbf7047 100644
--- a/drivers/net/ppp/pppoe.c
+++ b/drivers/net/ppp/pppoe.c
@@ -984,8 +984,10 @@
 	if (skb) {
 		total_len = min_t(size_t, total_len, skb->len);
 		error = skb_copy_datagram_iovec(skb, 0, m->msg_iov, total_len);
-		if (error == 0)
-			error = total_len;
+		if (error == 0) {
+			consume_skb(skb);
+			return total_len;
+		}
 	}
 
 	kfree_skb(skb);