moduleLoad.c needs to support using the new module only RT CPU isolation interface, and the Bullseye Kernel SMP calls.

Debian 11's (bullseye) 5.10 kernel changes the old cpu_up()/cpu_down() SPM calls with add_cpu()/remove_cpu().

The src/drv/rts-cpu-isolator module also exports is_cpu_taken_by_rcg_model and set_fe_code_idle - so we can remove the local externs. It also provides a new interface for starting/stopping the RT code.