lv_hal: add init funtion to call prior driver registration

lv_hal/lv_hal_indev.c

@@ -36,6 +36,18 @@ static lv_indev_t *indev_list = NULL;
  *   GLOBAL FUNCTIONS
  **********************/
 
+/**
+ * Initialize an input device driver with default values.
+ * It is used to surly have known values in the fields ant not memory junk.
+ * After it you can set the fields.
+ * @param driver pointer to driver variable to initialize
+ */
+void lv_indev_drv_init(lv_indev_drv_t *driver)
+{
+    driver->read_fp = NULL;
+    driver->type = LV_INDEV_TYPE_NONE;
+}
+
 /**
  * Register an initialized input device driver.
  * @param driver pointer to an initialized 'lv_indev_drv_t' variable (can be local variable)