Change in coreboot[master]: mb/intel/shadowmountain: Add flash layout for shadowmountain

[V Sowmya (Code Review)]

Attention is currently required from: Sugnan Prabhu S, Tim Wawrzynczak, Subrata Banik, Balaji Manigandan, Aamir Bohra.
V Sowmya has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/49478 )

Change subject: mb/intel/shadowmountain: Add flash layout for shadowmountain
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Patch Set 2:

(1 comment)

File src/mainboard/intel/shadowmountain/chromeos.fmd:

https://review.coreboot.org/c/coreboot/+/49478/comment/299a47ab_dd58ea42 
PS1, Line 6: SI_BIOS@0x1400000 0xc00000 {
> i think the idea is here to create 12MB BIOS region hence started from bottom alignment

ACK