rpmsg: Only invoke announce_create for rpdev with endpoints

For special rpmsg devices without a primary endpoint there is nothing to
announce so don't call the backend announce create function if we didn't
create an endpoint.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/rpmsg/rpmsg_core.c

@@ -442,7 +442,7 @@ static int rpmsg_dev_probe(struct device *dev)
 		goto out;
 	}
 
-	if (rpdev->ops->announce_create)
+	if (ept && rpdev->ops->announce_create)
 		err = rpdev->ops->announce_create(rpdev);
 out:
 	return err;