ACPICA: Namespace: fix memory leak from building prefixed pathname

ACPICA commit f8ca5db30605467b851f86d152079631c27eeca8

Link: https://github.com/acpica/acpica/commit/f8ca5db3


Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>