sdei_watchdog: avoid possible false hardlockup

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LQCC


CVE: NA

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Firmware may not trigger SDEI event as required frequency. SDEI event
may be triggered too soon, which cause false hardlockup in kernel. Check
the time stamp in sdei_watchdog_callbak and skip the hardlockup check if
it is invoked too soon.

Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>

 Conflicts:
	arch/arm64/kernel/watchdog_sdei.c (context conflict)
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>