[SPARK-6980] Missed one usage of deprecated RpcUtils.askTimeout in YarnSchedulerBackend although it is not being used, and fixed SparkConfSuite UT to not use deprecated RpcUtils functions

Author: BryanCutler

core/src/main/scala/org/apache/spark/scheduler/cluster/YarnSchedulerBackend.scala

@@ -46,7 +46,7 @@ private[spark] abstract class YarnSchedulerBackend(
   private val yarnSchedulerEndpoint = rpcEnv.setupEndpoint(
     YarnSchedulerBackend.ENDPOINT_NAME, new YarnSchedulerEndpoint(rpcEnv))
 
-  private implicit val askTimeout = RpcUtils.askTimeout(sc.conf)
+  private implicit val askTimeout = RpcUtils.askRpcTimeout(sc.conf)
 
   /**
    * Request executors from the ApplicationMaster by specifying the total number desired.

core/src/test/scala/org/apache/spark/SparkConfSuite.scala

@@ -260,10 +260,10 @@ class SparkConfSuite extends SparkFunSuite with LocalSparkContext with ResetSyst
     assert(RpcUtils.retryWaitMs(conf) === 2L)
 
     conf.set("spark.akka.askTimeout", "3")
-    assert(RpcUtils.askTimeout(conf) === (3 seconds))
+    assert(RpcUtils.askRpcTimeout(conf).duration === (3 seconds))
 
     conf.set("spark.akka.lookupTimeout", "4")
-    assert(RpcUtils.lookupTimeout(conf) === (4 seconds))
+    assert(RpcUtils.lookupRpcTimeout(conf).duration === (4 seconds))
   }
 }