powerpc: 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: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index b2b8447..c8e7333 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1195,7 +1195,7 @@
 	chip->irq_eoi(&desc->irq_data);
 }
 
-static struct irq_domain_ops mpic_host_ops = {
+static const struct irq_domain_ops mpic_host_ops = {
 	.match = mpic_host_match,
 	.map = mpic_host_map,
 	.xlate = mpic_host_xlate,