x86: Constify irqdomain ops

Nothing changes those ops. Make the initializers readable while at it.

Reported-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 1c7dd42..4264968 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -330,9 +330,9 @@
 	return err;
 }
 
-static struct irq_domain_ops x86_vector_domain_ops = {
-	.alloc = x86_vector_alloc_irqs,
-	.free = x86_vector_free_irqs,
+static const struct irq_domain_ops x86_vector_domain_ops = {
+	.alloc	= x86_vector_alloc_irqs,
+	.free	= x86_vector_free_irqs,
 };
 
 int __init arch_probe_nr_irqs(void)