armv8: zynqmp: Map PCIe High as device memory

Set the 8GB PCIe High area as device memory.
Also extend the DDR High area to cover the full 32GB range.

Signed-off-by: Anders Hedlund <anders.j.hedlund@gmail.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>