util/nvmutil: tidy up includes

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

util/nvmutil/nvmutil.c

@@ -7,22 +7,14 @@
  * These images configure your Intel Gigabit Ethernet adapter.
  */
 
-#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"