mac80211: Don't merge with the same BSSID

It was not a good idea to do a TSF reset on strange IBSS merges to the same BSSID. For example it will break the TSF sync of ath9k completely and it is unnecessary as all hardware I have tested do a TSF sync to a higher value automatically and IBSS merges are only done to higher TSF values. It only need a TSF reset to accept a lower value, when the IBSS network is changed manually.
Signed-off-by: NAlina Friedrichsen <x-alina@gmx.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/ibss.c

@@ -291,6 +291,10 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 				sdata->u.ibss.ssid_len))
 		goto put_bss;
 
+	/* same BSSID */
+	if (memcmp(bss->cbss.bssid, sdata->u.ibss.bssid, ETH_ALEN) == 0)
+		goto put_bss;
+
 	if (rx_status->flag & RX_FLAG_TSFT) {
 		/*
 		 * For correct IBSS merging we need mactime; since mactime is