selftests: sched: Fix spelling mistake "hiearchy" -> "hierarchy"

There is a spelling mistake in a printed message. Fix it.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: ColinIanKing

tools/testing/selftests/sched/cs_prctl_test.c

@@ -276,7 +276,7 @@ int main(int argc, char *argv[])
 	if (setpgid(0, 0) != 0)
 		handle_error("process group");
 
-	printf("\n## Create a thread/process/process group hiearchy\n");
+	printf("\n## Create a thread/process/process group hierarchy\n");
 	create_processes(num_processes, num_threads, procs);
 	need_cleanup = 1;
 	disp_processes(num_processes, procs);