Change in coreboot[master]: soc/intel/xeon_sp/cpx: Allow creating meminfo for empty DIMM slots

[Nico Huber (Code Review)]

Attention is currently required from: Anjaneya "Reddy" Chagam, Jonathan Zhang, Christian Walter, Angel Pons, Arthur Heymans, Tim Chu.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/64036 )

Change subject: soc/intel/xeon_sp/cpx: Allow creating meminfo for empty DIMM slots
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Patch Set 1:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/64036/comment/be720807_6073d741 
PS1, Line 9: Introduce the mainboard-defined `mainboard_dimm_slot_exists()` function
Wouldn't a simple Kconfig number do? It's hard to tell without seeing
the mb implementation.