qosmngr: accumulation of stats done based on driver does read and reset of stats or read.

src/qosmngr.c

@@ -222,10 +222,10 @@ static int prepare_stats_blob(struct blob_buf *b, struct qos_stats *stats, void
 
 	index = get_interface_index(ifname);
 
-	q_stat[index][qid].tx_packets += stats->tx_packets;
-	q_stat[index][qid].tx_bytes += stats->tx_bytes;
-	q_stat[index][qid].tx_dropped_packets += stats->tx_dropped_packets;
-	q_stat[index][qid].tx_dropped_bytes += stats->tx_dropped_bytes;
+	q_stat[index][qid].tx_packets = stats->tx_packets;
+	q_stat[index][qid].tx_bytes = stats->tx_bytes;
+	q_stat[index][qid].tx_dropped_packets = stats->tx_dropped_packets;
+	q_stat[index][qid].tx_dropped_bytes = stats->tx_dropped_bytes;
 
 	dd = blobmsg_open_table(b, "");