ACPICA: Clean up comment divergences in aclinux.h

When the following commmit is back ported to ACPICA, comments have been
updated:
  Subject: ACPICA: Linux-specific header: Update support for Linux/acpi
           applications.

This patch back ports the differences between the ACPICA upstream and
Linux.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
[rjw: Subject]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>