Fix the read input device example in README.md

README.md

@@ -144,7 +144,7 @@ indev_drv.type = LV_INDEV_TYPE_POINTER;    /*Touch pad is a pointer-like device*
 indev_drv.read_cb = my_touchpad_read;      /*Set your driver function*/
 lv_indev_drv_register(&indev_drv);         /*Finally register the driver*/
 
-bool my_touchpad_read(lv_indev_t * indev, lv_indev_data_t * data)
+bool my_touchpad_read(lv_indev_drv_t * indev_driver, lv_indev_data_t * data)
 {
     static lv_coord_t last_x = 0;
     static lv_coord_t last_y = 0;