perf spark: Fix includes and add SPDX

scnprintf is declared in linux/kernel.h, directly depend upon it.
Add missing SPDX comments.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250710235126.1086011-4-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/util/spark.c

@@ -1,9 +1,7 @@
-#include <stdio.h>
-#include <limits.h>
-#include <string.h>
-#include <stdlib.h>
+// SPDX-License-Identifier: GPL-2.0
 #include "spark.h"
-#include "stat.h"
+#include <limits.h>
+#include <linux/kernel.h>
 
 #define SPARK_SHIFT 8
 

tools/perf/util/spark.h

@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef SPARK_H
 #define SPARK_H 1