Select proper clock for the USB I2C API.
Select proper clock for the USB I2C API.

Once a USB connection is made, PLL1 is switched to 'max speed' at 204MHz;
but the current API incorrectly assumes PLL1 will be 48MHz, and selects too
low an I2C scaling factor accordingly.

This switches to the max_speed configuration appropriate for a PLL of 204MHz.

greatscottgadgets/greatfet,dominicgs/GreatFET-experimental,dominicgs/GreatFET-experimental,greatscottgadgets/greatfet,dominicgs/GreatFET-experimental,greatscottgadgets/greatfet,greatscottgadgets/greatfet