mfd: wm831x: Fix possible NULL pointer dereference

The driver always checks for pdata being NULL except in one place.
Add a check to prevent a possible NULL pointer deference error.
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/wm831x-core.c

@@ -1626,6 +1626,8 @@ int wm831x_device_init(struct wm831x *wm831x, unsigned long id, int irq)
 	mutex_init(&wm831x->io_lock);
 	mutex_init(&wm831x->key_lock);
 	dev_set_drvdata(wm831x->dev, wm831x);
+
+	if (pdata)
 		wm831x->soft_shutdown = pdata->soft_shutdown;
 
 	ret = wm831x_reg_read(wm831x, WM831X_PARENT_ID);