greybus: call put_device() on error

As soon as we've called device_initialize() we're required to call
put_device() in order to drop our reference to the device structure.
This was missed in the error path in greybus_new_module().  Fix that.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/core.c

@@ -440,6 +440,7 @@ struct greybus_device *greybus_new_module(struct device *parent,
 
 	return gdev;
 error:
+	put_device(&gdev->dev);
 	greybus_module_release(&gdev->dev);
 	return NULL;
 }