Change in coreboot[master]: arch/x86/smbios.c: Add SMBIOS type 17 for empty DIMM slots

[Johnny Lin (Code Review)]

Attention is currently required from: Arthur Heymans, Patrick Rudolph, Paul Menzel, Jingle Hsu, Angel Pons, Nill Ge, Marc Jones, Nico Huber, Subrata Banik, lichenchen.carl, Tim Chu, Shelly Chang.
Johnny Lin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/63882 )

Change subject: arch/x86/smbios.c: Add SMBIOS type 17 for empty DIMM slots
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Patch Set 8:

(1 comment)

Patchset:

PS8:
> You could invert `bool present` to `bool empty` or similar, so that the default value doesn't change […]

I plan to use an enum for dimm->present's value, because when a DIMM is not present but also doesn't exist on the board, setting it to false can still lead to creating an empty dimm slot table. So something like
enum dimm_present {
    EMPTY_DIMM_SLOT	= 1,
    INSTALLED_DIMM_SLOT	= 2,
    /* For DIMM that are not present and doesn't exist on the board. */
    IGNORED_DIMM	= 0xff
};

smbios.c:
if (dimm->present == EMPTY_DIMM_SLOT) {
    create empty DIMM table
} else if (dimm->present != IGNORED_DIMM) {
    create normal/installed DIMM table
}