virgl: Fix build regression of commit 8a943564

src/gallium/drivers/virgl/virgl_context.c

@@ -943,7 +943,7 @@ struct pipe_context *virgl_context_create(struct pipe_screen *pscreen,
    virgl_init_so_functions(vctx);
 
    list_inithead(&vctx->to_flush_bufs);
-   slab_create_child(&vctx->texture_transfer_pool, rs->texture_transfer_pool);
+   slab_create_child(&vctx->texture_transfer_pool, &rs->texture_transfer_pool);
 
    vctx->primconvert = util_primconvert_create(&vctx->base, rs->caps.caps.v1.prim_mask);
    vctx->uploader = u_upload_create(&vctx->base, 1024 * 1024,