Added basic dts support for MicroZed board.

- UART
- SDHCI
- Ethernet

Cc: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Jagan Teki <jteki@openedev.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>