kthread: unexport __kthread_should_park()

There are no in-kernel users of __kthread_should_park() so mark it as
static and do not export it.

Link: https://lkml.kernel.org/r/2023080450-handcuff-stump-1d6e@gregkh
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Cc: John Stultz <[e-mail]>
Cc: "Peter Zijlstra (Intel)" <[e-mail]>
Cc: "Arve Hjønnevåg" <[e-mail]>
Cc: Valentin Schneider <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: "Christian Brauner (Microsoft)" <[e-mail]>
Cc: Mike Christie <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Zqiang <[e-mail]>
Cc: Prathu Baronia <[e-mail]>
Cc: Sami Tolvanen <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

include/linux/kthread.h

···
 int kthread_stop(struct task_struct *k);
 bool kthread_should_stop(void);
 bool kthread_should_park(void);
-bool __kthread_should_park(struct task_struct *k);
 bool kthread_should_stop_or_park(void);
 bool kthread_freezable_should_stop(bool *was_frozen);
 void *kthread_func(struct task_struct *k);

kernel/kthread.c

···
 }
 EXPORT_SYMBOL(kthread_should_stop);
 
-bool __kthread_should_park(struct task_struct *k)
+static bool __kthread_should_park(struct task_struct *k)
 {
 	return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags);
 }
-EXPORT_SYMBOL_GPL(__kthread_should_park);
 
 /**
  * kthread_should_park - should this kthread park now?