Change in coreboot[master]: lib: Treat dimm addr_map 0 as not exist

[Jakub Czapiga (Code Review)]

Attention is currently required from: Tim Wawrzynczak, Ivy Jian, Eric Lai, Lean Sheng Tan.
Jakub Czapiga has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/63628 )

Change subject: lib: Treat dimm addr_map 0 as not exist
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Patch Set 5:

(5 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/63628/comment/4851bded_1adb39ac 
PS3, Line 7: not exist
nit: Maybe "invalid" is better word? Or "non-existent".

https://review.coreboot.org/c/coreboot/+/63628/comment/72967ddc_b1c325d9 
PS3, Line 9: not exist
Same as above.

https://review.coreboot.org/c/coreboot/+/63628/comment/4e1a179e_3567c588 
PS3, Line 10: there no HW exist
no HW exists
or
HW is unabailable / Hw is not present

File src/lib/spd_cache.c:

https://review.coreboot.org/c/coreboot/+/63628/comment/5c4c8d4e_0a916fb7 
PS2, Line 159: is not exist
"does not exist"

File tests/lib/spd_cache-test.c:

https://review.coreboot.org/c/coreboot/+/63628/comment/bf8575e7_298c75c1 
PS3, Line 143: 
Can you add test case with .addr_map containing zero? New fragment of code should be covered by tests.