I doubt you can turn it off. Just select the help option and it will tell you the dependencies, for this one they are:
Code:
┌────────────────────────── CPU idle PM support ──────────────────────────┐
│ CONFIG_CPU_IDLE: │
│ │
│ CPU idle is a generic framework for supporting software-controlled │
│ idle processor power management. It includes modular cross-platform │
│ governors that can be swapped during runtime. │
│ │
│ If you're using an ACPI-enabled platform, you should say Y here. │
│ │
│ Symbol: CPU_IDLE [=y] │
│ Prompt: CPU idle PM support │
│ Defined at drivers/cpuidle/Kconfig:2 │
│ Location: │
│ -> Power management and ACPI options │
│ Selected by: ACPI [=y] && !IA64_HP_SIM [=IA64_HP_SIM] && (IA64 [=IA64 ] || X86 [=y]) && PCI [=y] && PM [=y] │
You would have to disable PM = power management or PCI, which is a bad idea.