syzbot is reporting hung task at __input_unregister_device() [1], for
iforce_close() waiting at wait_event_interruptible() with dev->mutex held
is blocking input_disconnect_device() from __input_unregister_device().

It seems that the cause is simply that commit c2b27ef6 ("Input:
iforce - wait for command completion when closing the device") forgot to
call wake_up() after clear_bit().

Fix this problem by introducing a helper that calls clear_bit() followed
by wake_up_all().
Reported-by: syzbot <syzbot+deb6abc36aad4008f407@syzkaller.appspotmail.com>
Fixes: c2b27ef6 ("Input: iforce - wait for command completion when closing the device")
Tested-by: syzbot <syzbot+deb6abc36aad4008f407@syzkaller.appspotmail.com>
Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Co-developed-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/887021c3-4f13-40ce-c8b9-aa6e09faa3a7@I-love.SAKURA.ne.jp
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>