Utilities: Add new set of macros to support unalignment/endianness.

This patch introduces a set of macros to support combined unalignment and
endianness. We can use ACPI_DECODE/ENCODE(x) to improve existing code with
this combination supported in the following components:
  tables, parser, resource, disassembler
Then we might be able to delete old sets of macros after that.  Lv Zheng.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Tables: Improve AcpiTbGetRootTableEntry() using new unalignment/endianness combined macros.

This patch enhances the root table entry decoding code with both
unalignment and endianness supported.  Lv Zheng.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>