[XS] Change in coreboot[master]: acpi: Set checksum for SPCR table

[Nico Huber (Code Review)]

Attention is currently required from: Felix Singer, Lance Zhao, Lean Sheng Tan, Tim Wawrzynczak.

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/76158?usp=email )

Change subject: acpi: Set checksum for SPCR table
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Patch Set 1:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/76158/comment/0be06c85_3d50242a :
PS1, Line 13: Fixes: commit 90464073e4a1 (acpi: Add SPCR table)
> Odd enough that's a different log than I looked at before :D and this […]

Here's the log that mentions the checksum:
https://lava.9esec.io/scheduler/job/170839#results_9301823
```
[    1.474906] ACPI BIOS Warning (bug): Incorrect checksum in table [SPCR] - 0x00, should be 0x8B (20190703/tbprint-173)
```

But the fwts errors seem unrelated and spurious (https://learn.microsoft.com/en-us/windows-hardware/drivers/serports/serial-p...).

File src/acpi/acpi.c:

https://review.coreboot.org/c/coreboot/+/76158/comment/44a3b906_8e5f3a42 :
PS1, Line 1870: 	header->checksum = acpi_checksum((void *)spcr, header->length);
> Doesn't `length` need to be adjusted too? […]

It's just one struct with a constant length.