ARM: dts: add Ebang EBAZ4205 device tree

ARM: dts: add Ebang EBAZ4205 device tree

The Ebang EBAZ4205 is a simple board based on the Xilinx Zynq-7000 SoC.
Its features are:
 - one serial port
 - 256 MB RAM
 - 128 MB NAND flash
 - SDcard slot
 - IP101GA 10/100 Mbit Ethernet PHY (connected to PL IOs)
 - two LEDs (connected to PL IOs)
 - one Push Button (connect to PL IOs)
 - (optional) RTC
 - (optional) Input voltage supervisor

The NAND flash is not supported in mainline linux yet. Unfortunately,
the PHY is connected via the PL, thus for working ethernet the FPGA has
to be configured. Also, depending on the board variant, the PHY has no
external crystal and its clock needs to be driven by the PL. FCLK3 is
used for this and is kept enabled.

Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20210120194033.26970-4-michael@walle.cc
Signed-off-by: Michal Simek <michal.simek@xilinx.com>