pci: Add driver for Broadcom BCM2711 SoC PCIe controller

pci: Add driver for Broadcom BCM2711 SoC PCIe controller

This patch adds basic driver PCI Express controller found on Broadcom
set-top-box SoCs, e.g. BCM2711.
The code is based on Linux upstream driver (pcie-brcmstb.c) with MSI
handling removed. The inbound access memory region is not currently
parsed from dma-ranges DT property and a fixed 3GB region is used.

The patch has been tested on RPI4 board, i.e. on BCM2711 SoC with VL805
USB Host Controller.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>