zynq: Add zynq_zc770 xm013 board support

ZC770 is a complete development board based on the Xilinx Zynq-7000
All Programmable SoC, similar to ZC70x board but which has four
different daughter cards, like XM010, XM011, XM012 and XM013

ZC770 XM013:
- 1GB DDR3
- 128 Mb Quad-SPI Flash(dual parallel)
- USB-UART

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>