修复品牌列表页收藏状态错误的bug（uid为空时也传递到接口导致，改为不传uid参数）

Code Review By Rock Zhang

@@ -96,7 +96,11 @@ class BrandData
         // 构建必传参数
         $param = Yohobuy::param();
         $param['brand_id'] = $brandId;
-        $param['uid'] = $uid;
+
+        if (!empty($uid)) {
+            $param['uid'] = $uid;
+        }
+
         $param['method'] = 'app.brand.getBrandIntro';
         $param['client_secret'] = Sign::getSign($param);