[S] Change in coreboot[main]: security/vboot: Add Kconfig option to clear recovery request

[Yu-Ping Wu (Code Review)]

Attention is currently required from: Julius Werner, Michał Żygowski.

Yu-Ping Wu has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/74343?usp=email )

Change subject: security/vboot: Add Kconfig option to clear recovery request
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Patch Set 6:

(1 comment)

File src/security/vboot/bootmode.c:

https://review.coreboot.org/c/coreboot/+/74343/comment/6ce716e8_3eaa93bf :
PS4, Line 68: BS_ON_ENTRY
> Julius, ping

Let's proceed with your latest PS. If Julius has a different opinion, we can change it in the future.

For now, could you add a comment explaining why this has to be `BS_ON_ENTRY`?

```
/* This has to be called before back_up_vbnv_cmos, so BS_ON_ENTRY is used here. */
```