This is because the DCDC 3V15 on the EVK board has not enable yet. The ethernet port, which is powered by the DCDC, will not function until the DCDC has turned on.
It is unfortunately that the control logic of DCDC 3V15 in BSP release L2.6.35_11.04.01_ER is reverse to that required by the EVK board. The BSP should set the GPIO4_16 pin to level '1' instead of '0' to enable DCDC 3V15. The patch
L2.6.35_11.04.01_ER__mx50_rd3_DCDC3V15_fix.zip here should address this problem.
