update:sfud demo改为先擦出再写

demo/sfud/Air101/main.lua

@@ -17,7 +17,7 @@ sys.taskInit(function()
     log.info("sfud.init",sfud.init(spi_flash))
     log.info("sfud.getDeviceNum",sfud.getDeviceNum())
     local sfud_device = sfud.getDeviceTable()
-    log.info("sfud.write",sfud.write(sfud_device,1024,"sfud"))
+    log.info("sfud.eraseWrite",sfud.eraseWrite(sfud_device,1024,"sfud"))
     log.info("sfud.read",sfud.read(sfud_device,1024,4))
     log.info("sfud.mount",sfud.mount(sfud_device,"/sfud"))
     log.info("fsstat", fs.fsstat("/sfud"))