arm64: zynqmp: Describe ethernet phy on kd240

Describe ADIN phy present on KD240 via ethernet-phy-id compatible string.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/61f89dc055f191fd4138b80bb7e3217d814502f5.1702904236.git.michal.simek@amd.com