gcc-4.6: ACPI: fix unused but set variables in ACPI

Some minor improvements in error handling, but overall it was mostly dead
code.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>