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, Tim Wawrzynczak, Sugnan Prabhu S, Balaji Manigandan, Aamir Bohra.
Hello build bot (Jenkins), Patrick Georgi, Martin Roth, Sugnan Prabhu S, Tim Wawrzynczak, Angel Pons, Subrata Banik, Balaji Manigandan, Aamir Bohra,

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

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

to look at the new patch set (#6).

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

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/early_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, 283 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/79/49479/6