[M] Change in flashrom[main]: tree: Retype variable `is_laptop` to enum

[Peter Marheine (Code Review)]

Attention is currently required from: Aarya, Anastasia Klimchuk, Edward O'Callaghan.

Peter Marheine has posted comments on this change by Aarya. ( https://review.coreboot.org/c/flashrom/+/83834?usp=email )

Change subject: tree: Retype variable `is_laptop` to enum
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Patch Set 3:

(3 comments)

File dmi.c:

https://review.coreboot.org/c/flashrom/+/83834/comment/8fdd8139_95b4149f?usp... :
PS3, Line 67:  *	- 0: in all likelihood not a laptop
            :  *	- 1: in all likelihood a laptop
            :  *	- 2: chassis-type is not specific enough
> This need to be updated (there are no numbers anymore, enum instead)

I'd prefer to move this documentation to the enum definition, too.

File internal.c:

https://review.coreboot.org/c/flashrom/+/83834/comment/573903b4_7cf9f7d2?usp... :
PS3, Line 113: 	if ((is_laptop != YES) || laptop_ok)
Original here was `is_laptop == NO`; this would incorrectly assume `UNKNOWN` is not a laptop, which is specifically handled by the branch on line 121.

https://review.coreboot.org/c/flashrom/+/83834/comment/44599618_de335bff?usp... :
PS3, Line 230: bcfg.is_laptop == YES
> Strictly speaking, the previous code is equivalent to bcfg. […]

The double negative makes it difficult to follow, so I think rewording the comment would help.

```
/*
 * Disable internal buses if this might be a laptop, unless overridden.
 */
if (bcfg.is_laptop != NO && !(bcfg.laptop_ok || force_laptop || (not_a_laptop && bcfg.is_laptop == UNKNOWN))
```