zynq-common: Enable phy driver for Xilinx PCS/PMA core

Add support of Xilinx PCS/PMA core phy for Zynq

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>