添加了不需要由 PWM 或 引脚 控制LCD背光时的背光控制空函数，防止编译报错

bsp/stm32/libraries/HAL_Drivers/drv_lcd.c

@@ -254,6 +254,11 @@ void turn_on_lcd_backlight(void)
 
     rt_pin_write(LCD_DISP_GPIO_NUM, PIN_HIGH);
     rt_pin_write(LCD_BL_GPIO_NUM, PIN_HIGH);
+}
+#else
+void turn_on_lcd_backlight(void)
+{
+    
 }
 #endif