[M] Change in coreboot[main]: arch/riscv: add new SBI calls

[Martin L Roth (Code Review)]

Attention is currently required from: Arthur Heymans, Maximilian Brune, Philipp Hug, ron minnich.

Martin L Roth has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/81294?usp=email )

Change subject: arch/riscv: add new SBI calls
......................................................................

Patch Set 9:

(3 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/81294/comment/1add95d5_8264a3e6 :
PS9, Line 15: clang-formatted-by: Ronald G Minnich
This is odd. Is it needed?

Typically the Signed-off-by line is right next to the Change-ID line.  I don't think it's an issue, but the commit message looks unusual.

File src/arch/riscv/sbi.c:

https://review.coreboot.org/c/coreboot/+/81294/comment/7314615f_fa6a4ebc :
PS9, Line 97: __weak
I kind of hate this. Weak functions are bad enough, but weak arrays? Yuck.

Can we do this with a #define instead?

```
#ifndef SBI_FEATURE_VALUES
#define SBI_FEATURE_VALUES 1,0,0,0,0,0,0
#endif

int sbi_features[] = {SBI_FEATURE_VALUES};
```
Then the older SOCs can just define SBI_FEATURE_VALUES in their own header or something?

https://review.coreboot.org/c/coreboot/+/81294/comment/9c833ed6_b9156164 :
PS9, Line 120: if (0)
maybe `if (SBI_DEBUG)` and put that #define at the top of the file?