I want use i2c-3. I read that DP_AUX_P and DP_AUX_N pins should be used as SDA and SCL for i2c-3. However in the schematics, they are shown as pulled down to ground. I checked in voltage in these pins and its indeed grounded. How can I use these pins for i2c? Do I need to change pin functions? Or add external pullup resistor?