PCI: zynqmp: Add ZynqMP NWL PCIe root port driver

PCI: zynqmp: Add ZynqMP NWL PCIe root port driver

This patch adds the PCIe controller driver for the Xilinx / AMD ZynqMP
NWL PCIe Bridge as root port. The driver source is partly copied from
the Linux PCI driver and modified to enable usage in U-Boot (e.g.
simplified and interrupt support removed).

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Pali Rohár <pali@kernel.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Michal Simek <michal.simek@amd.com>
Tested-by: Michal Simek <michal.simek@amd.com>
Acked-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20230525094918.111949-1-sr@denx.de
Signed-off-by: Michal Simek <michal.simek@amd.com>