mac80211: Fixing slow IBSS rejoin

This patch fixes the issue of slow reconnection to an IBSS cell after
disconnection from it. Now the interface's bssid is reset upon ifdown.

ieee80211_sta_find_ibss:
if (found && memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0 &&
	    (bss = ieee80211_rx_bss_get(dev, bssid,
					local->hw.conf.channel->center_freq,
					ifsta->ssid, ifsta->ssid_len)))

Note:
In general disconnection is still not handled properly in mac80211
Signed-off-by: NAssaf Krauss <assaf.krauss@intel.com>
Signed-off-by: NTomas Winkler <tomas.winkler@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/main.c

@@ -511,6 +511,7 @@ static int ieee80211_stop(struct net_device *dev)
 	case IEEE80211_IF_TYPE_STA:
 	case IEEE80211_IF_TYPE_IBSS:
 		sdata->u.sta.state = IEEE80211_DISABLED;
+		memset(sdata->u.sta.bssid, 0, ETH_ALEN);
 		del_timer_sync(&sdata->u.sta.timer);
 		/*
 		 * When we get here, the interface is marked down.