wireless: correctly report signal value for IEEE80211_HW_SIGNAL_UNSPEC

This part was missed in "cfg80211: implement get_wireless_stats",
probably because sta_set_sinfo already existed and was only handling
dBm signals.

Cc: stable@kernel.org
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/cfg.c

@@ -354,7 +354,8 @@ static void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo)
 	sinfo->rx_packets = sta->rx_packets;
 	sinfo->tx_packets = sta->tx_packets;
 
-	if (sta->local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
+	if ((sta->local->hw.flags & IEEE80211_HW_SIGNAL_DBM) ||
+	    (sta->local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)) {
 		sinfo->filled |= STATION_INFO_SIGNAL;
 		sinfo->signal = (s8)sta->last_signal;
 	}