Hi,
we test ETH only with linux, it's much easier and works mostly out of the box.
Xilinx baremetal apps for eth works seldom out of the box.
At first check with our reference design (Boot.bin and image.ub are included in the prebuilt folder), if ETH works and that you has no other problem.
If this works, check at first MDIO access to PHY (maybe you use wrong PHY address?).
br
John