Interface claiming does not fit OpenBSD's USB stack

[mpi]

The OpenBSD backend that relies on the ugen(4) driver to access USB devices doesn't do any useful check in its claim_interface() and release_interface() functions.

In fact, it's not possible to open the same device more than once at the same time. In other words, there is a lock in the driver and only the first consumer of the API will be able to call claim_interface() and release_interface(), the others will not be able to open the device.