sdei_watchdog: set secure timer period base on 'watchdog_thresh'

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


CVE: NA

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The period of the secure timer is set to 3s by BIOS. That means the
secure timer interrupt will trigger every 3 seconds. To further decrease
the NMI watchdog's effect on performance, this patch set the period of
the secure timer base on 'watchdog_thresh'. This variable is initiallized
to 10s. We can also set the period at runtime by modifying
'/proc/sys/kernel/watchdog_thresh'

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>