util/nvmutil: tidy up includes

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/nvmutil/lib/string.c

@@ -1,25 +1,14 @@
 /* SPDX-License-Identifier: MIT
- *
  * Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
  *
  * String handling.
  */
 
-#ifdef __OpenBSD__
-#include <sys/param.h>
-#endif
 #include <sys/types.h>
 #include <sys/stat.h>
 
 #include <errno.h>
-#include <fcntl.h>
-#include <limits.h>
-#include <stdarg.h>
 #include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
 #include <unistd.h>
 
 #include "../include/common.h"