nl80211: send the NL80211_ATTR_SSID in nl80211_send_iface()

The userspace may want to know what is the current ssid that a given
interface is using. This patch enables nl80211 to send the
NL80211_ATTR_SSID attribute in nl80211_send_iface().
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -1787,6 +1787,11 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag
 			goto nla_put_failure;
 	}
 
+	if (wdev->ssid_len) {
+		if (nla_put(msg, NL80211_ATTR_SSID, wdev->ssid_len, wdev->ssid))
+			goto nla_put_failure;
+	}
+
 	return genlmsg_end(msg, hdr);
 
  nla_put_failure: