fix some variables not used warnings when build. (#7925)

components/drivers/wlan/wlan_dev.c

@@ -123,9 +123,7 @@ rt_err_t rt_wlan_dev_connect(struct rt_wlan_device *device, struct rt_wlan_info
 rt_err_t rt_wlan_dev_fast_connect(struct rt_wlan_device *device, struct rt_wlan_info *info, const char *password, int password_len)
 {
     rt_err_t result = RT_EOK;
-    struct rt_wlan_buff buff;
-
-    int len = 0;
+    struct rt_wlan_buff buff = {0};
 
     if (device == RT_NULL)
     {
@@ -372,8 +370,8 @@ rt_err_t rt_wlan_dev_unregister_event_handler(struct rt_wlan_device *device, rt_
 
 void rt_wlan_dev_indicate_event_handle(struct rt_wlan_device *device, rt_wlan_dev_event_t event, struct rt_wlan_buff *buff)
 {
-    void *parameter[RT_WLAN_DEV_EVENT_NUM];
-    rt_wlan_dev_event_handler handler[RT_WLAN_DEV_EVENT_NUM];
+    void *parameter[RT_WLAN_DEV_EVENT_NUM] = {0};
+    rt_wlan_dev_event_handler handler[RT_WLAN_DEV_EVENT_NUM] = {0};
     int i;
     rt_base_t level;
 

components/drivers/wlan/wlan_mgnt.c

@@ -842,7 +842,6 @@ static void rt_wlan_join_scan_callback(int event, struct rt_wlan_buff *buff, voi
 {
     struct rt_wlan_info *info = RT_NULL;
     struct rt_wlan_info *tgt_info = RT_NULL;
-    int ret = RT_EOK;
 
     RT_ASSERT(event == RT_WLAN_EVT_SCAN_REPORT);
     RT_ASSERT(buff != RT_NULL);
@@ -880,7 +879,6 @@ rt_err_t rt_wlan_connect(const char *ssid, const char *password)
     struct rt_wlan_info info;
     struct rt_wlan_complete_des *complete;
     rt_uint32_t set = 0, recved = 0;
-    rt_uint32_t scan_retry = RT_WLAN_SCAN_RETRY_CNT;
 
     /* sta dev Can't be NULL */
     if (_sta_is_null())
@@ -1584,7 +1582,6 @@ rt_err_t rt_wlan_scan_with_info(struct rt_wlan_info *info)
     rt_err_t err = RT_EOK;
     struct rt_wlan_complete_des *complete;
     rt_uint32_t set = 0, recved = 0;
-    static struct rt_wlan_info scan_filter_info;
 
     if (_sta_is_null())
     {