Change in coreboot[master]: libpayload/pci: Add PCIe interfaces for MediaTek platform

[Jianjun Wang (Code Review)]

Attention is currently required from: Hung-Te Lin, Paul Menzel, Angel Pons, Jianjun Wang.
Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/56794

to look at the new patch set (#13).

Change subject: libpayload/pci: Add PCIe interfaces for MediaTek platform
......................................................................

libpayload/pci: Add PCIe interfaces for MediaTek platform

Add PCIe configuration interfaces for MediaTek platform.

The register base address of PCIe hardware might be different when it's
a non-x86 platform, add 'pci_update_hw_base()' interface for users to
update its base address to access PCIe hardware correctly.

TEST=Build pass and boot up to kernel successfully via SSD on Cherry
board, here is the SSD information in boot log:
 == NVME IDENTIFY CONTROLLER DATA ==
    PCI VID   : 0x1987
    PCI SSVID : 0x1987
    SN        : 28F40713077B0012602
    MN        : Phison ESE1A043-X28
    RAB       : 0x1
    AERL      : 0x3
    SQES      : 0x66
    CQES      : 0x44
    NN        : 0x1
Identified NVMe model Phison ESE1A043-X28

BUG=b:178565024

Signed-off-by: Jianjun Wang 
Change-Id: I9ea7d111fed6b816fa2352fe93c268116519a577
---
M payloads/libpayload/Kconfig
M payloads/libpayload/drivers/Makefile.inc
A payloads/libpayload/drivers/pcie_mediatek.c
M payloads/libpayload/include/pci.h
4 files changed, 48 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/94/56794/13