irqchip/orion: Use of_address_count() helper

After commit 16988c742968 ("of/address: introduce of_address_count() helper"),
Use of_address_count() to instead of open-coding it, it's no functional change.

Signed-off-by: Yang Yingliang <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/irqchip/irq-orion.c

···
 	struct resource r;
 
 	/* count number of irq chips by valid reg addresses */
-	while (of_address_to_resource(np, num_chips, &r) == 0)
-		num_chips++;
+	num_chips = of_address_count(np);
 
 	orion_irq_domain = irq_domain_add_linear(np,
 				num_chips * ORION_IRQS_PER_CHIP,