As several cpufreq drivers are late_initcalls now [dependency on acpi/processor.c
which is module_init()], we need to use Makefile ordering to assert that
- speedstep-centrino is loaded before acpi [faster: msr instead of io]
- speedstep-centrino, speedstep-ich and acpi are loaded before p4-clockmod
  [frequency and voltage scaling instead of throttling]