venus: Only claim modifiers in WSI if the host driver supports it

Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34218>

src/virtio/vulkan/vn_wsi.c

@@ -87,7 +87,8 @@ vn_wsi_init(struct vn_physical_device *physical_dev)
    if (result != VK_SUCCESS)
       return result;
 
-   physical_dev->wsi_device.supports_modifiers = true;
+   physical_dev->wsi_device.supports_modifiers =
+      physical_dev->base.vk.supported_extensions.EXT_image_drm_format_modifier;
    physical_dev->base.vk.wsi_device = &physical_dev->wsi_device;
 
    return VK_SUCCESS;