sched_ext: idle: Remove unnecessary ifdef in scx_bpf_cpu_node()

There's no need to make scx_bpf_cpu_node() dependent on CONFIG_NUMA,
since cpu_to_node() can be used also in systems with CONFIG_NUMA
disabled.

This also allows to always validate the @cpu argument regardless of the
CONFIG_NUMA settings.

Fixes: 0105921 ("sched_ext: idle: Introduce node-aware idle cpu kfunc helpers")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Author: arighi

kernel/sched/ext_idle.c

@@ -929,14 +929,10 @@ s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
  */
 __bpf_kfunc int scx_bpf_cpu_node(s32 cpu)
 {
-#ifdef CONFIG_NUMA
 	if (!kf_cpu_valid(cpu, NULL))
 		return NUMA_NO_NODE;
 
 	return cpu_to_node(cpu);
-#else
-	return 0;
-#endif
 }
 
 /**