Added debug print to identify failed pyusb info queries.
Added debug print to identify failed pyusb info queries.

- Permission issues seem to be raised as ValueErrors from pyusb with
  "The device has no langid" as the message.
- The debug print just prints out the ValueError message string.

pyocd/pyOCD,flit/pyOCD,mbedmicro/pyOCD,mbedmicro/pyOCD,pyocd/pyOCD,flit/pyOCD,mesheven/pyOCD,mesheven/pyOCD,mbedmicro/pyOCD,mesheven/pyOCD