Ctrl-c fix for linux

This patch fixes the ctrl-c bug for linux when running on newer kernels.  This is likely a terrible hack, but it appears to make things better.  The descriptor changes are simply hacks, but they appear to help.  The descriptor changes only affect USB 3.0 connections.  It has different affects on different hosts:
- Windows hosts didn't have a problem before, and still don't have a problem
- Old linux kernels (3.8 tested) no longer kernel panic, however things aren't great.  After ctrl-c'ing, it takes a reset of the bladeRF to re-run the repeater test.  I have also seen my XHCI driver stop detecting the bladeRF.  
- New linux kernels (3.11 tested) work much nicer,  Still get some messages in dmesg, but the repeater can be ctrl-c'd and run again without incident.

The descriptor change feels like a terrible hack, but it appears to be positive change.