mux: core: fix double get_device()

class_find_device already does a get_device on the returned device.
So the device returned by of_find_mux_chip_by_node is already referenced
and we should not reference it again (and unref it on error).

Signed-off-by: Hans de Goede <[e-mail]>
Signed-off-by: Peter Rosin <[e-mail]>
Cc: stable <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/mux/core.c

···
 	return dev->of_node == data;
 }
 
+/* Note this function returns a reference to the mux_chip dev. */
 static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
 {
 	struct device *dev;
···
 	    (!args.args_count && (mux_chip->controllers > 1))) {
 		dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n",
 			np, args.np);
+		put_device(&mux_chip->dev);
 		return ERR_PTR(-EINVAL);
 	}
 
···
 	if (controller >= mux_chip->controllers) {
 		dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n",
 			np, controller, args.np);
+		put_device(&mux_chip->dev);
 		return ERR_PTR(-EINVAL);
 	}
 
-	get_device(&mux_chip->dev);
 	return &mux_chip->mux[controller];
 }
 EXPORT_SYMBOL_GPL(mux_control_get);