[coreboot-gerrit] Change in coreboot[master]: mb/intel/shadowmountain: Add the romstage code

[Aamir Bohra (Code Review)]

Attention is currently required from: V Sowmya, Martin Roth, Tim Wawrzynczak, Angel Pons, Balaji Manigandan.
Aamir Bohra has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/49731 )

Change subject: mb/intel/shadowmountain: Add the romstage code
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Patch Set 5: Code-Review+2