Add the 2xCortexR5 CPUs to zynqmp board. They are powered off on reset
(this is true of real hardware) by default or selectable as the boot
processor.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: da34128c73ca13fc4f8c3293e1a33d1e1e345655.1434501320.git.peter.crosthwaite@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>