mfd: fix da903x warning

The da903x interrupt handler is retruning an int instead of an irqreturn_t.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/da903x.c b/drivers/mfd/da903x.c
index 99f8dcf..7283d88 100644
--- a/drivers/mfd/da903x.c
+++ b/drivers/mfd/da903x.c
@@ -413,7 +413,7 @@
 	enable_irq(chip->client->irq);
 }
 
-static int da903x_irq_handler(int irq, void *data)
+static irqreturn_t da903x_irq_handler(int irq, void *data)
 {
 	struct da903x_chip *chip = data;