kernel/sched/sched.h: Exclude cpuidle from KABI

Bugzilla: https://bugzilla.redhat.com/2033340
Depends: https://bugzilla.redhat.com/2024595
Depends: !326 (merged)

Upstream Status: RHEL9 only

Exclude the cpuidle_state struct from KABI calculations. task_struct is
a protected struct, but the CPU IDLE data is only used by internal
function.

To make this commit easier to find in future string searches:
RH_KABI kabi rh_kabi.

Signed-off-by: Prarit Bhargava prarit@redhat.com