arm64: zynqmp: Adding prefetchable memory space to pcie node

Adding prefetchable memory space to pcie device tree node.
Shifting configuration space to 64-bit address space.
Removing pcie device tree node from amba as it requires size-cells=<2>
in order to access 64-bit address space.

Signed-off-by: Bharat Kumar Gogada <bharatku@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>