The function rte_eth_from_ring does not really do what it says on the tin.
The programmer would expect that the ring passed would be used to make an
ethdev.
Instead the name is used as a seed to a new ring name ETH_RXTX0_XXXX.

Not sure if it ever did the right thing.

One would expect the passed in ring would become the ring used for the ethdev.
Instead the passed in ring is never used.