Change in coreboot[master]: mb/intel/shadowmountain: Add bootblock and verstage code

[V Sowmya (Code Review)]

Attention is currently required from: V Sowmya, Martin Roth.
Hello build bot (Jenkins), Patrick Georgi, Martin Roth,

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

https://review.coreboot.org/c/coreboot/+/49479

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

Change subject: mb/intel/shadowmountain: Add bootblock and verstage code
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mb/intel/shadowmountain: Add bootblock and verstage code

This patch includes the bootblock and verstage changes for
shadowmountain board.

BUG=b:175808146
TEST= Build and boot shadowmountain board till early romstage.

Signed-off-by: V Sowmya 
Change-Id: I5f805baf42203306ff10e91a258d9117dd986c4a
---
M src/mainboard/intel/shadowmountain/Kconfig
A src/mainboard/intel/shadowmountain/Makefile.inc
A src/mainboard/intel/shadowmountain/bootblock.c
A src/mainboard/intel/shadowmountain/chromeos.c
A src/mainboard/intel/shadowmountain/variants/baseboard/Makefile.inc
M src/mainboard/intel/shadowmountain/variants/baseboard/devicetree.cb
A src/mainboard/intel/shadowmountain/variants/baseboard/gpio.c
A src/mainboard/intel/shadowmountain/variants/baseboard/include/baseboard/gpio.h
A src/mainboard/intel/shadowmountain/variants/baseboard/include/baseboard/variants.h
9 files changed, 285 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/79/49479/2