irqchip/ts4800: Make ts4800_ic_ops static const

ts4800_ic_ops is only referenced in this driver, so make it static.
In additional, it's never get modified thus also make it const.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Link: https://lkml.kernel.org/r/1455457804.13175.1.camel@ingics.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-ts4800.c

@@ -59,7 +59,7 @@ static int ts4800_irqdomain_map(struct irq_domain *d, unsigned int irq,
 	return 0;
 }
 
-struct irq_domain_ops ts4800_ic_ops = {
+static const struct irq_domain_ops ts4800_ic_ops = {
 	.map = ts4800_irqdomain_map,
 	.xlate = irq_domain_xlate_onecell,
 };