ACPI: Documentation: Fix path for acpidbg tool

The file:

Documentation/acpi/aml-debugger.txt

reports an obsolete path for the acpidbg tool, so fix it.

Signed-off-by: Flavio Suligoi <f.suligoi@asem.it>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>