ACPI / debugger: Fix an issue a flag is modified without locking

There is one line of code, executed out of locking due to rebase mistakes.
This patch fixes this issue.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
1 file changed