YARN-7707. Fix CheckStyle.

Author: slfan1989

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-globalpolicygenerator/src/main/java/org/apache/hadoop/yarn/server/globalpolicygenerator/GlobalPolicyGenerator.java

@@ -136,9 +136,9 @@ protected void serviceStart() throws Exception {
     }
 
     // Schedule PolicyGenerator
-    long policyGeneratorIntervalMillis = getConfig().getLong(
+    long policyGeneratorIntervalMillis = config.getTimeDuration(
         YarnConfiguration.GPG_POLICY_GENERATOR_INTERVAL_MS,
-        YarnConfiguration.DEFAULT_GPG_POLICY_GENERATOR_INTERVAL_MS);
+        YarnConfiguration.DEFAULT_GPG_POLICY_GENERATOR_INTERVAL_MS, TimeUnit.MILLISECONDS);
     if(policyGeneratorIntervalMillis > 0){
       this.scheduledExecutorService.scheduleAtFixedRate(this.policyGenerator,
           0, policyGeneratorIntervalMillis, TimeUnit.MILLISECONDS);