irqdomain: Use irq_domain_get_of_node() instead of direct field access

The struct irq_domain contains a "struct device_node *" field
(of_node) that is almost the only link between the irqdomain
and the device tree infrastructure.

In order to prepare for the removal of that field, convert all
users to use irq_domain_get_of_node() instead.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-and-tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Tomasz Nowicki <tomasz.nowicki@linaro.org>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Cc: Graeme Gregory <graeme@xora.org.uk>
Cc: Jake Oshins <jakeo@microsoft.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Link: http://lkml.kernel.org/r/1444737105-31573-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/powerpc/platforms/cell/spider-pic.c

@@ -231,20 +231,23 @@ static unsigned int __init spider_find_cascade_and_node(struct spider_pic *pic)
 	const u32 *imap, *tmp;
 	int imaplen, intsize, unit;
 	struct device_node *iic;
+	struct device_node *of_node;
+
+	of_node = irq_domain_get_of_node(pic->host);
 
 	/* First, we check whether we have a real "interrupts" in the device
 	 * tree in case the device-tree is ever fixed
 	 */
-	virq = irq_of_parse_and_map(pic->host->of_node, 0);
+	virq = irq_of_parse_and_map(of_node, 0);
 	if (virq)
 		return virq;
 
 	/* Now do the horrible hacks */
-	tmp = of_get_property(pic->host->of_node, "#interrupt-cells", NULL);
+	tmp = of_get_property(of_node, "#interrupt-cells", NULL);
 	if (tmp == NULL)
 		return NO_IRQ;
 	intsize = *tmp;
-	imap = of_get_property(pic->host->of_node, "interrupt-map", &imaplen);
+	imap = of_get_property(of_node, "interrupt-map", &imaplen);
 	if (imap == NULL || imaplen < (intsize + 1))
 		return NO_IRQ;
 	iic = of_find_node_by_phandle(imap[intsize]);