intel_idle: Use subsys_initcall_sync() for initialization

It is not necessary to wait until the device_initcall() stage with
intel_idle initialization.  All of its dependencies are met after
all subsys_initcall()s have run, so subsys_initcall_sync() can be
used for initializing it.

It is also better to ensure that intel_idle will always initialize
before the ACPI processor driver that uses module_init() for its
initialization.

Signed-off-by: Rafael J. Wysocki <[email protected]>
Tested-by: Artem Bityutskiy <[email protected]>
Link: https://patch.msgid.link/[email protected]

drivers/idle/intel_idle.c

@@ -2518,7 +2518,7 @@ init_driver_fail:
 	return retval;
 
 }
-device_initcall(intel_idle_init);
+subsys_initcall_sync(intel_idle_init);
 
 /*
  * We are not really modular, but we used to support that.  Meaning we also