The original code assumes that calls to PIO_ConfigureIt() are only
made once e.g. during board start-up. Hoewever, we call those
at USB SetConfiguration time, when we know which particular hardware
function we are supposed to perform. This means that after the host
has issued SetConfiguration more than a given number of times, the
code will assert() due to overflow of the static array.
Let's check if we already have allocated an array slot for a given pin
and reuse that allocated array bucket rather than allocating new ones
for the same pin.