ipack: Handle a driver without remove callback

A driver that only consumes devm-managed resources might well have no
remove callback. Additionally given that the device core ignores the return
value of ipack_bus_remove() stop returning an error code.

Signed-off-by: Uwe Kleine-König <[e-mail]>
Acked-by: Samuel Iglesias Gonsalvez <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/ipack/ipack.c

···
 	struct ipack_device *dev = to_ipack_dev(device);
 	struct ipack_driver *drv = to_ipack_driver(device->driver);
 
-	if (!drv->ops->remove)
-		return -EINVAL;
+	if (drv->ops->remove)
+		drv->ops->remove(dev);
 
-	drv->ops->remove(dev);
 	return 0;
 }