Cosmetic fixes and comment additions in acpi.c.

Cosmetic fixes and comment additions in acpi.c.

 - Fix whitespace, coding style, and indentation in some places.

 - Add comments for less obvious entries and hardcoded numbers (e.g. 'type').

 - Add comments for all/most 'revision' fields, mention in which version
   of the ACPI spec which revision number is to be used.

 - Add URLs to a few external documents which describe tables that are
   not mentioned in the ACPI spec (or where the external document may
   provide further info), e.g. SRAT, SLIT, HPET, MCFG, etc.

 - Use the ASLC #define instead of hardcoding "CORE" in one instance
   (ASLC is already used everywhere else).

 - Add some TODOs for additional stuff which is in the spec but not yet
   handled by our code / #defines.

Abuild-tested.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6098 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1