Detach kernel driver before claiming USB2 ANT+ interface.

Kernel 3.11 exposes the Suunto ANT+ stick as a USB serial device,
this prevents GC from opening it in training mode unless the
kernel driver is detached first.
Detach kernel driver before claiming USB2 ANT+ interface.

Only detach kernel driver if compiling under Linux (not a portable function)..
Merge pull request #690 from dresco/master

Detach kernel driver before claiming USB2 ANT+ interface.