ACPI: fix section for CPU init functions

The ACPI processor init functions should be marked as __cpuinit as they use
structures marked with __cpuinitdata.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Len Brown <len.brown@intel.com>