irq: change references from NR_IRQS to nr_irqs

Impact: preparation, cleanup, add KERN_INFO printk

Modify references from NR_IRQS to nr_irqs as the later will become
variable-sized based on nr_cpu_ids when CONFIG_SPARSE_IRQS=y.

Signed-off-by: Mike Travis <travis@sgi.com>
diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 1337eab..ae80638 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -3183,7 +3183,7 @@
 
 	irq = 0;
 	spin_lock_irqsave(&vector_lock, flags);
-	for (new = irq_want; new < NR_IRQS; new++) {
+	for (new = irq_want; new < nr_irqs; new++) {
 		if (platform_legacy_irq(new))
 			continue;