Recently I did some testing with RFC2217 and it is possible to get it working with bindings. 
The issue isn’t that there is no discovery implementation in the RFC2217PortProvider. The issue is that the ZWave binding has a workaround which results in that only discovered ports can be used. I’ve created issue #1332 for that.
Another issue is that some methods throw exceptions when used with a RFC2217 port.
It also helps to not limit serial port options in UIs so users can enter RFC2217 port details.
I made some changes for all of that in this commit.
Since I don’t have a ZWave controller, maybe someone can help testing if these changes make it possible to use RFC2217 connections with ZWave by testing this org.openhab.binding.zwave-2.5.5-SNAPSHOT.jar?