On Xilinx ZynqMP revA board initial value of PHYCR register is 0x5448 which
means FORCE_LINK_GOOD is already setup. Origin code was doing write but the
new code is doing read/modify/write and keep this bit untouched. That's why
ethernet stop to work.
The patch is cleaning this bit when PHYCR value is composed.
Tested on Xilinx zcu102-revA and zcu104-rev1.0 boards.