ARM64: zynqmp: Add ocm node in dtsi

This patch adds ocm controller node in zynqmp.dtsi.
needed for OCM edac support.

Signed-off-by: Naga Sureshkumar Relli <nagasure@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>