drivers/mtd:init commit of power-loss resilient cfg

Signed-off-by: 田昕 <tianxin7@xiaomi.com>

include/nuttx/mtd/configdata.h

@@ -120,6 +120,21 @@ extern "C"
 struct mtd_dev_s;
 int mtdconfig_register(FAR struct mtd_dev_s *mtd);
 
+/****************************************************************************
+ * Name: mtdconfig_unregister
+ *
+ * Description:
+ *   This function unregisters /dev/config device.
+ *
+ * Input Parameters:
+ *
+ * Returned Value:
+ *   Zero on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int mtdconfig_unregister(void);
+
 #undef EXTERN
 #ifdef __cplusplus
 }