genirq: Introduce helper function irq_data_get_node()

Introduce helper function irq_data_get_node() and variants thereof to
hide struct irq_data implementation details.

Convert the core code to use them.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: http://lkml.kernel.org/r/1433145945-789-5-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index b1c7e8f..f974485 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -363,7 +363,7 @@
 setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 {
 	struct cpumask *set = irq_default_affinity;
-	int node = desc->irq_data.node;
+	int node = irq_desc_get_node(desc);
 
 	/* Excludes PER_CPU and NO_BALANCE interrupts */
 	if (!irq_can_set_affinity(irq))