hw/arm: xlnx: Set all boards' GEM 'phy-addr' property value to 23

When cadence_gem model was created for Xilinx boards, the PHY address
was hard-coded to 23 in the GEM model. Now that we have introduced a
property we can use that to tell GEM model what our PHY address is.
Change all boards' GEM 'phy-addr' property value to 23, and set the
PHY address default value to 0 in the GEM model.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <1598924352-89526-13-git-send-email-bmeng.cn@gmail.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>