[bsp][stm32f4xx-HAL] fix iwg driver.

bsp/stm32f4xx-HAL/drivers/drv_iwg.c

@@ -32,7 +32,7 @@ static rt_err_t drv_control(rt_watchdog_t *wdt, int cmd, void *arg)
     switch (cmd)
     {
     case RT_DEVICE_CTRL_WDT_SET_TIMEOUT:
-        hiwdg.Init.Reload = (rt_uint32_t)arg;
+        hiwdg.Init.Reload = (rt_uint32_t)*arg;
         if (HAL_IWDG_Init(&hiwdg) != HAL_OK)
         {
             return RT_ERROR;