ConnectCore8x - U-boot and ENET0


We use I2C3 on the ConnectCore8x multiplexed to pins 109/110, which works fine. However, during boot, the pins get jammed by u-boot trying to establish a PHY connection through ENET0 (same pins).

Is there a way of switching this off without recompiling and flashing u-boot? If not, do you have any instructions how to do it?