mfd: MAX8998/LP3974 hibernation support

This patch makes the driver to save and restore register values
for hibernation.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/max8998-irq.c b/drivers/mfd/max8998-irq.c
index c6b61fc..3903e1f 100644
--- a/drivers/mfd/max8998-irq.c
+++ b/drivers/mfd/max8998-irq.c
@@ -183,6 +183,13 @@
 	return IRQ_HANDLED;
 }
 
+int max8998_irq_resume(struct max8998_dev *max8998)
+{
+	if (max8998->irq && max8998->irq_base)
+		max8998_irq_thread(max8998->irq_base, max8998);
+	return 0;
+}
+
 int max8998_irq_init(struct max8998_dev *max8998)
 {
 	int i;