intel_idle: Move and clean up intel_idle_cpuidle_devices_uninit()

Move intel_idle_cpuidle_devices_uninit() closer to its caller,
intel_idle_init(), add the __init modifier to its header, drop a
redundant local variable from it and fix up its kerneldoc comment.

No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/idle/intel_idle.c

@@ -1296,21 +1296,6 @@ static inline void intel_idle_init_cstates_acpi(struct cpuidle_driver *drv) { }
 static inline bool intel_idle_off_by_default(u32 mwait_hint) { return false; }
 #endif /* !CONFIG_ACPI_PROCESSOR_CSTATE */
 
-/*
- * intel_idle_cpuidle_devices_uninit()
- * Unregisters the cpuidle devices.
- */
-static void intel_idle_cpuidle_devices_uninit(void)
-{
-	int i;
-	struct cpuidle_device *dev;
-
-	for_each_online_cpu(i) {
-		dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
-		cpuidle_unregister_device(dev);
-	}
-}
-
 /*
  * ivt_idle_state_table_update(void)
  *
@@ -1565,6 +1550,17 @@ static int intel_idle_cpu_online(unsigned int cpu)
 	return 0;
 }
 
+/**
+ * intel_idle_cpuidle_devices_uninit - Unregister all cpuidle devices.
+ */
+static void __init intel_idle_cpuidle_devices_uninit(void)
+{
+	int i;
+
+	for_each_online_cpu(i)
+		cpuidle_unregister_device(per_cpu_ptr(intel_idle_cpuidle_devices, i));
+}
+
 static int __init intel_idle_init(void)
 {
 	const struct x86_cpu_id *id;