Looking in there, I see the empty directory, it could be that it has gone from beyond the indicated deprecation to effectively removed.
The Kernel NEVER had any direct access to I/O devices, those were always additional libraries with a machine dependent part. The key would be needing to find/write a compatible PCI driver for your machine. FreeRTOS-Plus-IO would have never been the full answer to your problem, it just defined a uniform API that drivers would support to allow generic access to them. You would have still needed to find the needed PCI driver to use too.