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

Simplify the scheduler by making CONFIG_SMP=y code in
add_nr_running() 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/20250528080924.2273858-43-mingo@kernel.org

Author: ingomolnar

kernel/sched/sched.h

@@ -2673,10 +2673,8 @@ static inline void add_nr_running(struct rq *rq, unsigned count)
 		call_trace_sched_update_nr_running(rq, count);
 	}
 
-#ifdef CONFIG_SMP
 	if (prev_nr < 2 && rq->nr_running >= 2)
 		set_rd_overloaded(rq->rd, 1);
-#endif
 
 	sched_update_tick_dependency(rq);
 }