um: virt-pci: set device ready in probe()

Call virtio_device_ready() to make this driver work after commit
b4ec69d7e09 ("virtio: harden vring IRQ"), since the driver uses the
virtqueues in the probe function. (The virtio core sets the device
ready when probe returns.)

Fixes: 8b4ec69d7e09 ("virtio: harden vring IRQ")
Fixes: 68f5d3f3b654 ("um: add PCI over virtio emulation driver")
Signed-off-by: Vincent Whitchurch <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
Tested-by: Johannes Berg <[e-mail]>

arch/um/drivers/virt-pci.c

···
 	dev->cmd_vq = vqs[0];
 	dev->irq_vq = vqs[1];
 
+	virtio_device_ready(dev->vdev);
+
 	for (i = 0; i < NUM_IRQ_MSGS; i++) {
 		void *msg = kzalloc(MAX_IRQ_MSG_SIZE, GFP_KERNEL);
 
···
 	dev->irq = irq_alloc_desc(numa_node_id());
 	if (dev->irq < 0) {
 		err = dev->irq;
-		goto error;
+		goto err_reset;
 	}
 	um_pci_devices[free].dev = dev;
 	vdev->priv = dev;
···
 
 	um_pci_rescan();
 	return 0;
+err_reset:
+	virtio_reset_device(vdev);
+	vdev->config->del_vqs(vdev);
 error:
 	mutex_unlock(&um_pci_mtx);
 	kfree(dev);