mfd: Provide the tc3589x with its own IRQ domain

In preparation for Device Tree enablement all IRQ controllers
should control their own IRQ domain. This patch provides just
that.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/include/linux/mfd/tc3589x.h b/include/linux/mfd/tc3589x.h
index 3acb3a8..6b8e1ff 100644
--- a/include/linux/mfd/tc3589x.h
+++ b/include/linux/mfd/tc3589x.h
@@ -117,6 +117,7 @@
 	struct mutex lock;
 	struct device *dev;
 	struct i2c_client *i2c;
+	struct irq_domain *domain;
 
 	int irq_base;
 	int num_gpio;