carl9170: fix signal strength reporting issues

On A-MPDU frames, the hardware only reports valid signal strength data for the last subframe.

This patch fixes it by flagging everything but the last subframe in an A-MPDU to tell mac80211 to ignore the signal strength entirely. Otherwise the empty value (= 0 dbm) will distort the average quite badly.

---
 drivers/net/wireless/ath/carl9170/rx.c |    2 ++
 1 file changed, 2 insertions(+)

index 6d22382..876a773 100644
@@ -814,6 +814,8 @@ static void carl9170_rx_untie_data(struct ar9170 *ar, u8 *buf, int len)
 
 	if (phy)
 		carl9170_rx_phy_status(ar, phy, &status);
+	else
+		status.flag |= RX_FLAG_NO_SIGNAL_VAL;
 
 	if (carl9170_handle_mpdu(ar, buf, mpdu_len, &status))
 		goto drop;

1.7.10.4