doc: trace: fix reference to cpuidle documentation file

mainline inclusion
from mainline-v5.0-rc2
commit 7604bf09
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V
CVE: NA

--------------------------------

Old cpuidle/sysfs.txt file was replaced in aa5eee35. So, refer to
an updated file.

Fixes: aa5eee35 (Documentation: admin-guide: PM: Add cpuidle document)
Signed-off-by: NOtto Sabart <ottosabart@seberm.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

Documentation/trace/coresight-cpu-debug.txt

@@ -165,7 +165,7 @@ Do some work...
 The same can also be done from an application program.
 
 Disable specific CPU's specific idle state from cpuidle sysfs (see
-Documentation/cpuidle/sysfs.txt):
+Documentation/admin-guide/pm/cpuidle.rst):
 # echo 1 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$state/disable