arm: dt: zynq-zed: Fix Ethernet phy address

arm: dt: zynq-zed: Fix Ethernet phy address

When Ethernet is brought up, the driver cannot find the phy. Correcting
the phy address fixes this issue, resulting in working Ethernet.

For Rev <= B the address is 7
For Rev >= C the address is 1

Setting up broadcast address 0 should work on all revisions.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Jason Wu <j.wu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>