ACPI: processor: idle: Relocate state flags initialization

ACPI: processor: idle: Relocate state flags initialization

Since acpi_processor_setup_cstates() is a more logical place for setting
idle state flags than acpi_processor_setup_cpuidle_cx(), move that code
from the latter to the former.

It also allows direct references to acpi_idle_driver in
acpi_processor_setup_cpuidle_cx() to be avoided.

No intentional functional impact.

Signed-off-by: Huisong Li <lihuisong@huawei.com>
[ rjw: Subject and changelog rewrite ]
Link: https://patch.msgid.link/20250929093754.3998136-5-lihuisong@huawei.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>