venus: fix a prime blit assert...again

The assert doesn't consider multiple queue family case where the same
blit cmd has to be recorded for each, thus hitting the assert for the
same image and buffer.

The prior fix of the same 054c8e117e was
accidentally missed in the reland of the implicit in-fence handling MR:
- https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39401

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/14843
Fixes: eb709cba47 ("venus: track prime blit dst buffer memory in the wsi image")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39871>

src/virtio/vulkan/vn_command_buffer.c

@@ -1488,7 +1488,7 @@ vn_CmdCopyImageToBuffer(VkCommandBuffer commandBuffer,
     */
    if (buf->wsi.mem) {
       assert(img->wsi.is_prime_blit_src);
-      assert(!img->wsi.blit_mem);
+      assert(!img->wsi.blit_mem || img->wsi.blit_mem == buf->wsi.mem);
       img->wsi.blit_mem = buf->wsi.mem;
    }