ACPICA: Silence a -Wbad-function-cast warning when acpi_uintptr_t is 'uintptr_t'

Do not pass the return value of strtoul() to the ACPI_TO_POINTER()
macro to avoid a -Wbad-function-cast warning.

Signed-off-by: Sascha Wildner <saw@online.de>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>