ARM: pxa: Constify irq_domain_ops

The irq_domain_ops are not modified by the driver and the irqdomain core
code accepts pointer to a const data.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>

arch/arm/mach-pxa/irq.c

@@ -138,7 +138,7 @@ static int pxa_irq_map(struct irq_domain *h, unsigned int virq,
 	return 0;
 }
 
-static struct irq_domain_ops pxa_irq_ops = {
+static const struct irq_domain_ops pxa_irq_ops = {
 	.map    = pxa_irq_map,
 	.xlate  = irq_domain_xlate_onecell,
 };