Add the latest stable Ettus-Research USRP Hardware Driver (UHD) Software and firmware images.
In contrast to comms/usrp it compiles only the host part and not the images.
The images are the binaries from ettus.

While the port compiles cleanly it doesn't fully work for my B200
but this could be a local HW problem since the B* series is picky about the USB3 HW...
Therefore this port is currently not connected to gnuradio.