Depending on which features (and thus USB configurations) are included
in the firmware, we need to re-define the ordering of the configuration
numbers, as the Atmel USBD driver simply assumes that configurations are
numbered 1..N without any gaps in the sequence.
The define PR was introduced to switch quickly between TRACE levels
for specific debug print messages.
Now, it all became debug output, since it is not needed in normal
operation.
