ACPICA: Tables: Merge DMAR table structure updates

This patch is a back port result of the following Linux commit:
  Author: David Woodhouse <David.Woodhouse@intel.com>
  Subject: iommu/vt-d: Add ACPI namespace device reporting structures

ACPICA need to handle old compilers where u8 object_name[] is only allowed
for an initialized variable. This patch reduces back port source code
differences between Linux and ACPICA upstream.

Cc: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>