dts: zynq: Add zynq qspi controller nodes

This patch adds zynq qspi controller nodes in zynq-7000.dtsi.

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>