sched/smp: Use the SMP version of rq_pin_lock()

Simplify the scheduler by making a CONFIG_SMP-only warning
in rq_pin_lock() 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/20250528080924.2273858-39-mingo@kernel.org

Author: ingomolnar

kernel/sched/sched.h

@@ -1745,9 +1745,7 @@ static inline void rq_pin_lock(struct rq *rq, struct rq_flags *rf)
 
 	rq->clock_update_flags &= (RQCF_REQ_SKIP|RQCF_ACT_SKIP);
 	rf->clock_update_flags = 0;
-#ifdef CONFIG_SMP
 	WARN_ON_ONCE(rq->balance_callback && rq->balance_callback != &balance_push_callback);
-#endif
 }
 
 static inline void rq_unpin_lock(struct rq *rq, struct rq_flags *rf)