vdpa: min vq num of vdpa device cannot be greater than max vq num

Just failed to probe the vdpa device if the min virtqueue num returned
by get_vq_num_min is greater than the max virtqueue num returned by
get_vq_num_max.
Signed-off-by: Wu Zongyong <wuzongyong@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/21199b62cc10b2a9f2cf90eeb63ad080645d881f.1635493219.git.wuzongyong@linux.alibaba.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/vdpa.c

@@ -26,8 +26,16 @@ static int vdpa_dev_probe(struct device *d)
 {
 	struct vdpa_device *vdev = dev_to_vdpa(d);
 	struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);
+	const struct vdpa_config_ops *ops = vdev->config;
+	u32 max_num, min_num = 1;
 	int ret = 0;
 
+	max_num = ops->get_vq_num_max(vdev);
+	if (ops->get_vq_num_min)
+		min_num = ops->get_vq_num_min(vdev);
+	if (max_num < min_num)
+		return -EINVAL;
+
 	if (drv && drv->probe)
 		ret = drv->probe(vdev);