Revert "ramdisk: tweak to speed up boot process"

This reverts commit fae67f4b4c5dbde058c607546b505263e7423e0e.

* pm2.c has implemented the boot_lock timeout(60s) for normal booting
  to avoid PM entering idle state, so this tweak seems useless.
* Also remove deprecated pm/idle_sleep_mode path

Change-Id: Icf353ec628bfd6b952ed0e4c7c543faa7a1d8dc1
overlay: clean up CPU frequencies

Change-Id: I17f6c4531daa68712d5e5f424c68c7862d5ef04e