!5110 电源服务示例代码修改

Merge pull request !5110 from 孙悦/master

zh-cn/application-dev/reference/apis/js-apis-power.md

@@ -234,7 +234,7 @@ setPowerMode(mode: DevicePowerMode, callback: AsyncCallback<void>): void
 **示例：**
 
 ```js
-power.setPowerMode(DevicePowerMode.MODE_PERFORMANCE, error => {
+power.setPowerMode(power.DevicePowerMode.MODE_PERFORMANCE, error => {
     if (typeof error === "undefined") {
         console.info('set power mode to MODE_PERFORMANCE');
     } else {
@@ -271,7 +271,7 @@ setPowerMode(mode: DevicePowerMode): Promise<void>
 **示例：**
 
 ```js
-power.setPowerMode(DevicePowerMode.MODE_PERFORMANCE)
+power.setPowerMode(power.DevicePowerMode.MODE_PERFORMANCE)
 .then(() => {
     console.info('set power mode to MODE_PERFORMANCE');
 })