irq_domain/c6x: constify irq_domain structures

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Mark Salter <msalter@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>

arch/c6x/kernel/irq.c

@@ -86,7 +86,7 @@ static int core_domain_map(struct irq_domain *h, unsigned int virq,
 	return 0;
 }
 
-static struct irq_domain_ops core_domain_ops = {
+static const struct irq_domain_ops core_domain_ops = {
 	.map = core_domain_map,
 };