drm/virtio: fix uninitialized variable

smatch reported this with the blob series:

drivers/gpu/drm/virtio/virtgpu_kms.c:227 virtio_gpu_init()
error: uninitialized symbol 'ret'.
Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20200902210847.2689-3-gurchetansingh@chromium.orgSigned-off-by: Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/virtio/virtgpu_kms.c

@@ -105,7 +105,7 @@ int virtio_gpu_init(struct drm_device *dev)
 	/* this will expand later */
 	struct virtqueue *vqs[2];
 	u32 num_scanouts, num_capsets;
-	int ret;
+	int ret = 0;
 
 	if (!virtio_has_feature(dev_to_virtio(dev->dev), VIRTIO_F_VERSION_1))
 		return -ENODEV;