Change in coreboot[master]: libpayload/pci: Add pci_map_bus function for MediaTek platform

[Jianjun Wang (Code Review)]

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

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

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

to look at the new patch set (#57).

Change subject: libpayload/pci: Add pci_map_bus function for MediaTek platform
......................................................................

libpayload/pci: Add pci_map_bus function for MediaTek platform

Add 'pci_map_bus' function and PCIE_MEDIATEK config for MediaTek
platform.

TEST=Build pass and boot up to kernel successfully via SSD on Dojo
board, here is the SSD information in boot log:
 == NVME IDENTIFY CONTROLLER DATA ==
    PCI VID   : 0x15b7
    PCI SSVID : 0x15b7
    SN        : 21517J440114
    MN        : WDC PC SN530 SDBPTPZ-256G-1006
    RAB       : 0x4
    AERL      : 0x7
    SQES      : 0x66
    CQES      : 0x44
    NN        : 0x1
Identified NVMe model WDC PC SN530 SDBPTPZ-256G-1006

BUG=b:178565024
BRANCH=cherry

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
3 files changed, 27 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/94/56794/57