sched/fair: Removed unsued cfs_rq.h_nr_delayed

h_nr_delayed is not used anymore. We now have:
 - h_nr_runnable which tracks tasks ready to run
 - h_nr_queued which tracks enqueued tasks either ready to run or
   delayed dequeue

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20241202174606.4074512-7-vincent.guittot@linaro.org