drm/virtio: Use dev_is_pci()

Use common dev_is_pci() helper to replace the strcmp("pci") used by driver.
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220630200726.1884320-9-dmitry.osipenko@collabora.comSigned-off-by: Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/virtio/virtgpu_drv.c

@@ -87,7 +87,7 @@ static int virtio_gpu_probe(struct virtio_device *vdev)
 		return PTR_ERR(dev);
 	vdev->priv = dev;
 
-	if (!strcmp(vdev->dev.parent->bus->name, "pci")) {
+	if (dev_is_pci(vdev->dev.parent)) {
 		ret = virtio_gpu_pci_quirk(dev);
 		if (ret)
 			goto err_free;