fw/rt_config: Avoid querying online cpus if hotplug disabled
fw/rt_config: Avoid querying online cpus if hotplug disabled

If the device does not have the hoptplug module installed, avoid
unnecessary querying of the device to check the number of cpus which
can cause issues with some devices.

setrofim/workload-automation,ARM-software/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,ARM-software/workload-automation