watchdog: make hardlockup detect code public

euler inclusion
category: feature
Bugzilla: 5515
CVE: N/A

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In current code, the hardlockup detect code is contained by
CONFIG_HARDLOCKUP_DETECTOR_PERF. This patch makes this code public so
that other arch hardlockup detector can use it.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>