ACPICA: iASL: Cleanup/optimization for ToPLD macro support

ACPICA commit 0e6125401cf38427d5376f4bafbfb3d5a40f8467

Use local variables for access to string/value Op fields.
Move duplicate PLD string tables to a single common table.

Link: https://github.com/acpica/acpica/commit/0e612540


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