The MAX11300EVKIT datasheet tells the user to connect +12.5V to AVDDIO and -12.5V to AVSSIO; however, the voltages are outside the range of power supply specifications given in the MAX11300 datasheet. The power supply specifications given by the MAX11300 datasheet are correct, and it is recommended that users follow these specifications. This means the user should apply +12V to AVDDIO and -12V to AVSSIO.
If you already connected +12.5V to AVDDIO and -12.5V to AVSSIO to your MAX11300EVKIT, do not worry. You did not cause any damage to the part. It is just recommeded that next time you power the MAX11300EVKIT you connect +12V to AVDDIO and -12V to AVSSIO.