ACPI: PCC: Fix unintentional integer overflow

Fix an unintentional u32 overflow by changing PCC_CMD_WAIT_RETRIES_NUM
to 500ULL.

Fixes: 91cefefb

 ("ACPI: PCC: replace wait_for_completion()")
Signed-off-by: Manank Patel <pmanank200502@gmail.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>