staging: vt6655: lock MACvWriteBSSIDAddress.

This function selects page 1 and cause intermittent problems on
interrupt handler.

lock call with spin_lock_irqsave.
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Cc: <stable@vger.kernel.org> # v3.19+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6655/device_main.c

@@ -1417,9 +1417,16 @@ static void vnt_bss_info_changed(struct ieee80211_hw *hw,
 
 	priv->current_aid = conf->aid;
 
-	if (changed & BSS_CHANGED_BSSID)
+	if (changed & BSS_CHANGED_BSSID) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&priv->lock, flags);
+
 		MACvWriteBSSIDAddress(priv->PortOffset, (u8 *)conf->bssid);
 
+		spin_unlock_irqrestore(&priv->lock, flags);
+	}
+
 	if (changed & BSS_CHANGED_BASIC_RATES) {
 		priv->basic_rates = conf->basic_rates;