Change in coreboot[master]: mainboard: Add Synology DS918+

[Name of user not set (Code Review)]

Attention is currently required from:  Felix Singer, Name of user not set #1003506, Martin Roth, Michael Niewöhner.
Hello  Felix Singer, build bot (Jenkins), Patrick Georgi, Martin Roth, Angel Pons, Michael Niewöhner,

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

https://review.coreboot.org/c/coreboot/+/52594

to look at the new patch set (#2).

Change subject: mainboard: Add Synology DS918+
......................................................................

mainboard: Add Synology DS918+

I'm new to coreboot.
This port is based on 4.13, this board boots. Tested with tianocore.
Can provide serial logs, original Synology's DSM OS works fine with this
port. Can run tests on my board.
Things todo:
* polish
* find out how to tell the OS that this board has no video output.
* make it work with master branch
* My gentoo UEFI stub kernel fail to load with "X64 Exception type - 06"
* ...

Patch set 1
Reformated gpio part and dsdt.

Here are serial logs:
https://clbin.com/tHOE7 -- Master branch
https://clbin.com/wp4R8 -- 4.13 + seabios, same code except 1 include in
dsdt
https://clbin.com/iUrgJ -- 4.13 + tianocore, same code...

Video test:
https://schizoden.xyz/videos/watch/816c5a68-af6f-4dd4-8c7e-43d068410822

Change-Id: Ib837e0819c97a617e5558480e7cdac05e3cff185
Signed-off-by: mkjOoB 
---
A src/mainboard/synology/Kconfig
A src/mainboard/synology/Kconfig.name
A src/mainboard/synology/ds918plus/Kconfig
A src/mainboard/synology/ds918plus/Kconfig.name
A src/mainboard/synology/ds918plus/Makefile.inc
A src/mainboard/synology/ds918plus/board_info.txt
A src/mainboard/synology/ds918plus/bootblock.c
A src/mainboard/synology/ds918plus/devicetree.cb
A src/mainboard/synology/ds918plus/ds918plus.fmd
A src/mainboard/synology/ds918plus/dsdt.asl
A src/mainboard/synology/ds918plus/gpio.h
A src/mainboard/synology/ds918plus/gpio_early.h
A src/mainboard/synology/ds918plus/mainboard.c
A src/mainboard/synology/ds918plus/romstage.c
14 files changed, 552 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/94/52594/2