uboot-imx

doc: device-tree-bindings: spi: Add zynq qspi info

Added device-tree-binding information for zynq qspi controller
driver.

Signed-off-by: Jagan Teki <jteki@openedev.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Jagan Teki <jteki@openedev.com>