sched/deadline: Use cpumask_weight_and() in dl_bw_cpus

cpumask_subset(a,b) -> cpumask_weight(a) should be same as cpumask_weight_and(a,b)
for_each_cpu_and(a,b) to count cpus could be replaced by cpumask_weight_and(a,b)

No Functional Change. It could save a few cycles since cpumask_weight_and
would be more efficient. Plus one less stack variable.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20251014100342.978936-3-sshegde@linux.ibm.com

Author: Shrikanth Hegde

kernel/sched/deadline.c

@@ -125,20 +125,11 @@ static inline struct dl_bw *dl_bw_of(int i)
 static inline int dl_bw_cpus(int i)
 {
 	struct root_domain *rd = cpu_rq(i)->rd;
-	int cpus;
 
 	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
 			 "sched RCU must be held");
 
-	if (cpumask_subset(rd->span, cpu_active_mask))
-		return cpumask_weight(rd->span);
-
-	cpus = 0;
-
-	for_each_cpu_and(i, rd->span, cpu_active_mask)
-		cpus++;
-
-	return cpus;
+	return cpumask_weight_and(rd->span, cpu_active_mask);
 }
 
 static inline unsigned long __dl_bw_capacity(const struct cpumask *mask)