intel_th: msu: Add a sysfs attribute to trigger window switch

mainline inclusion
from mainline-v5.2-rc1
commit 6cac7866
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V


CVE: NA

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Now that we have the means to trigger a window switch for the MSU trace
store, add a sysfs file to allow triggering it from userspace.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>