[SPARK-27215][CORE] Correct the kryo configurations

## What changes were proposed in this pull request?

```scala
val KRYO_USE_UNSAFE = ConfigBuilder("spark.kyro.unsafe")
    .booleanConf
    .createWithDefault(false)

  val KRYO_USE_POOL = ConfigBuilder("spark.kyro.pool")
    .booleanConf
    .createWithDefault(true)
```
**kyro should be kryo**

## How was this patch tested?

no need

Closes apache#24156 from LantaoJin/SPARK-27215.

Authored-by: Lantao Jin <[email protected]>
Signed-off-by: Marcelo Vanzin <[email protected]>

Author: LantaoJin

core/src/main/scala/org/apache/spark/internal/config/Kryo.scala

@@ -34,11 +34,11 @@ private[spark] object Kryo {
     .toSequence
     .createWithDefault(Nil)
 
-  val KRYO_USE_UNSAFE = ConfigBuilder("spark.kyro.unsafe")
+  val KRYO_USE_UNSAFE = ConfigBuilder("spark.kryo.unsafe")
     .booleanConf
     .createWithDefault(false)
 
-  val KRYO_USE_POOL = ConfigBuilder("spark.kyro.pool")
+  val KRYO_USE_POOL = ConfigBuilder("spark.kryo.pool")
     .booleanConf
     .createWithDefault(true)