[M] Change in coreboot[master]: soc/intel/xeon_sp: move PCH specific code into lbg directory

[Simon Chou (Code Review)]

Attention is currently required from: Jonathan Zhang, Johnny Lin, David Hendricks, Christian Walter, Angel Pons, Arthur Heymans, Tim Chu.

Simon Chou has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/72396 )

Change subject: soc/intel/xeon_sp: move PCH specific code into lbg directory
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Patch Set 3: Code-Review+1