[S] Change in coreboot[main]: commonlib: Add assembly optimization for ipchksum() on arm64

[Paul Menzel (Code Review)]

Attention is currently required from: Julius Werner.

Paul Menzel has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/80254?usp=email )

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Change subject: commonlib: Add assembly optimization for ipchksum() on arm64
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Patch Set 2:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/80254/comment/c5f9764c_139b33af :
PS2, Line 10: to take advantage of larger load
            : sizes and the add-with-carry instruction
Excuse my ignorance, but why can’t the compilers do that themselves?

https://review.coreboot.org/c/coreboot/+/80254/comment/7b2020f7_84cc71a7 :
PS2, Line 12: by more than 20x
Thank you for documenting this. Do you also have absolute timestamps? (I have no idea, where `ipchksum()` is used.)