regulator: Initialise wm831x structure pointor for ISINK driver

The version that made it into mainline missed the initialisation of the
chip handle.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/wm831x-isink.c

@@ -167,6 +167,8 @@ static __devinit int wm831x_isink_probe(struct platform_device *pdev)
 		return -ENOMEM;
 	}
 
+	isink->wm831x = wm831x;
+
 	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 	if (res == NULL) {
 		dev_err(&pdev->dev, "No I/O resource\n");