irqchip/renesas-irqc: Use linear IRQ domain

Use linear IRQ domain instead of irq_domain_add_simple() that also
handles non-DT cases. This reduces the delta between the IRQC code and
the generic chip implementation.
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Cc: jason@lakedaemon.net
Cc: geert+renesas@glider.be
Cc: horms@verge.net.au
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20150720100625.2552.63939.sendpatchset@little-appleSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/irqchip/irq-renesas-irqc.c

@@ -242,8 +242,8 @@ static int irqc_probe(struct platform_device *pdev)
 	irq_chip->irq_set_wake = irqc_irq_set_wake;
 	irq_chip->flags	= IRQCHIP_MASK_ON_SUSPEND;
 
-	p->irq_domain = irq_domain_add_simple(pdev->dev.of_node,
-					      p->number_of_irqs, 0,
+	p->irq_domain = irq_domain_add_linear(pdev->dev.of_node,
+					      p->number_of_irqs,
 					      &irqc_irq_domain_ops, p);
 	if (!p->irq_domain) {
 		ret = -ENXIO;