Add PCIe support for NVMe devices

[m5p3nc3r]

Enable PCIe support in the kernel. This requires that

• KERNEL_FEATURES includes pci.
• The KBI command is used to switch the firmware to PCI mode. Follow the instructions here https://docs.khadas.com/vim3/HowToSetupPcieUsbPort.html
• You need Linux 5.8 or later, so this works with the master Poky branch, not dunfell. It will compile with dunfell, you just won't have the PCIe enabled.
• You need to modify the device tree in the bootloader (fdt addr ${dtb_addr} 0x10000; fdt set /soc/pcie status "okay")

I have pulled in the kernel configuration for NVMe drivers only. The proper way is probably to include bsp/common-pc/... to pull in the required CONFIG_NVME_CORE and CONFIG_BLK_DEV_NVME. This pulls in a lot of additional drivers into the root filesystem and may have an x86 bias?

[superna9999]

Hi,

I pushed an automatic pcie enable for the next u-boot: https://github.com/u-boot/u-boot/commit/adbff64af7b7cee3e0007b75df2644090edaafcb

Including the corresponding documentation, maybe you can backport this patch on the current meta-meson u-boot recipe in addition to that