testing/ostest: align wdog ostest with wdog bugfix

    apache/nuttx#17293 fixed
    wd_start bug, and this patch fixed the related ostest
    accordingly

Signed-off-by: Chengdong Wang <wangchengdong@lixiang.com>

Author: wangchdo

testing/ostest/wdog.c

@@ -299,6 +299,7 @@ static void wdog_test_run(FAR wdtest_param_t *param)
   /* Maximum */
 
   delay = CLOCK_MAX >> 2;
+  delay -= 1;
   wdtest_assert(wd_start(&test_wdog, delay,
                          wdtest_callback, (wdparm_t)param) == OK);