xen/events: Switch to irq_get_nr_irqs()

Use the irq_get_nr_irqs() function instead of the global variable
'nr_irqs'. Prepare for changing 'nr_irqs' from an exported global
variable into a variable with file scope.

Signed-off-by: Bart Van Assche <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]

drivers/xen/events/events_base.c

···
 {
 	const struct irq_info *info = NULL;
 
-	if (likely(irq < nr_irqs))
+	if (likely(irq < irq_get_nr_irqs()))
 		info = info_for_irq(irq);
 	if (!info)
 		return 0;