irq: mips: replace cpumask_weight with cpumask_empty where appropriate

bcm6345_l1_of_init() calls cpumask_weight() to check if any bit of a given
cpumask is set. We can do it more efficiently with cpumask_empty() because
cpumask_empty() stops traversing the cpumask as soon as it finds first set
bit, while cpumask_weight() counts all bits unconditionally.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>

drivers/irqchip/irq-bcm6345-l1.c

@@ -315,7 +315,7 @@ static int __init bcm6345_l1_of_init(struct device_node *dn,
 			cpumask_set_cpu(idx, &intc->cpumask);
 	}
 
-	if (!cpumask_weight(&intc->cpumask)) {
+	if (cpumask_empty(&intc->cpumask)) {
 		ret = -ENODEV;
 		goto out_free;
 	}