[PATCH] rtl8187: ensure priv->hwaddr is always valid

conf->mac_addr is not guaranteed to be set. This ensures priv->hwaddr is
always set to a valid mac address. Thanks to Johannes Berg
<johannes@sipsolutions.net> for finding this problem.
Signed-off-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rtl8187_dev.c

@@ -466,7 +466,7 @@ static int rtl8187_add_interface(struct ieee80211_hw *dev,
 		return -EOPNOTSUPP;
 	}
 
-	priv->hwaddr = conf->mac_addr;
+	priv->hwaddr = conf->mac_addr ? conf->mac_addr : dev->wiphy->perm_addr;
 
 	return 0;
 }