hw/arm/xlnx: Fix PHY address for xilinx-zynq-a9

hw/arm/xlnx: Fix PHY address for xilinx-zynq-a9

Commit dfc388797cc4 ("hw/arm: xlnx: Set all boards' GEM 'phy-addr'
property value to 23") configured the PHY address for xilinx-zynq-a9
to 23. When trying to boot xilinx-zynq-a9 with zynq-zc702.dtb or
zynq-zc706.dtb, this results in the following error message when
trying to use the Ethernet interface.

macb e000b000.ethernet eth0: Could not attach PHY (-19)

The devicetree files for ZC702 and ZC706 configure PHY address 7. The
documentation for the ZC702 and ZC706 evaluation boards suggest that the
PHY address is 7, not 23. Other boards use PHY address 0, 1, 3, or 7.
I was unable to find a documentation or a devicetree file suggesting
or using PHY address 23. The Ethernet interface starts working with
zynq-zc702.dtb and zynq-zc706.dtb when setting the PHY address to 7,
so let's use it.

Cc: Bin Meng <bin.meng@windriver.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20210504124140.1100346-1-linux@roeck-us.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>