sched/smp: Use the SMP version of the stop-CPU scheduling class

Simplify the scheduler by making CONFIG_SMP=y code in the stop-CPU
scheduling class unconditional.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-36-mingo@kernel.org

Author: ingomolnar

kernel/sched/stop_task.c

@@ -9,7 +9,6 @@
  */
 #include "sched.h"
 
-#ifdef CONFIG_SMP
 static int
 select_task_rq_stop(struct task_struct *p, int cpu, int flags)
 {
@@ -21,7 +20,6 @@ balance_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 {
 	return sched_stop_runnable(rq);
 }
-#endif /* CONFIG_SMP */
 
 static void
 wakeup_preempt_stop(struct rq *rq, struct task_struct *p, int flags)
@@ -107,11 +105,9 @@ DEFINE_SCHED_CLASS(stop) = {
 	.put_prev_task		= put_prev_task_stop,
 	.set_next_task          = set_next_task_stop,
 
-#ifdef CONFIG_SMP
 	.balance		= balance_stop,
 	.select_task_rq		= select_task_rq_stop,
 	.set_cpus_allowed	= set_cpus_allowed_common,
-#endif
 
 	.task_tick		= task_tick_stop,