[S] Change in libgfxinit[master]: gma: Ensure global variable default are zeros and in .bss

[Jérémy Compostella (Code Review)]

Attention is currently required from: Nico Huber, Tarun Tuli, Angel Pons.

Jérémy Compostella has posted comments on this change. ( https://review.coreboot.org/c/libgfxinit/+/69855 )

Change subject: gma: Ensure global variable default are zeros and in .bss
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Patch Set 1:

(1 comment)

Patchset:

PS1: 
@Nico,

I am considering adding `hw__gfx__gma__initialized` into `car.ld` in place of this patch. What do you think ?

I have concerned that this patch is most likely going to break the checker. I would do it in https://review.coreboot.org/c/coreboot/+/70276 patch.