mfd: Store wm8350 struct in core device driver data

This will allow us to move to a more idiomatic MFD model as drivers
will be able to get the struct by looking at their parent device.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/mfd/wm8350-core.c b/drivers/mfd/wm8350-core.c
index e81cc31..dd1caaa 100644
--- a/drivers/mfd/wm8350-core.c
+++ b/drivers/mfd/wm8350-core.c
@@ -573,6 +573,8 @@
 	u16 id1, id2, mask_rev;
 	u16 cust_id, mode, chip_rev;
 
+	dev_set_drvdata(wm8350->dev, wm8350);
+
 	/* get WM8350 revision and config mode */
 	ret = wm8350->read_dev(wm8350, WM8350_RESET_ID, sizeof(id1), &id1);
 	if (ret != 0) {