[M] Change in coreboot[main]: sb/intel/common: Add GPIO serial blink console support

[Nicholas Chin (Code Review)]

Attention is currently required from: Intel coreboot Reviewers, Jérémy Compostella, Keith Hui.

Nicholas Chin has posted comments on this change by Keith Hui. ( https://review.coreboot.org/c/coreboot/+/86390?usp=email )

Change subject: sb/intel/common: Add GPIO serial blink console support
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Patch Set 1:

(2 comments)

File Documentation/technotes/console.md:

https://review.coreboot.org/c/coreboot/+/86390/comment/419f97c2_378d5f6a?usp... :
PS1, Line 172: [Intel 7-series PCH](https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/7-se...)
             : datasheet
It would be good to mention the Intel document number for this (326776) as these links often break.

File src/southbridge/intel/common/gpio.c:

https://review.coreboot.org/c/coreboot/+/86390/comment/2a9412cc_db50b6eb?usp... :
PS1, Line 195: CONSOLE_INTEL_GPSB)
> Because static get_gpio_base(). […]

`console/` seems to be for backend independent console code, so it wouldn't go there. Maybe somewhere in `drivers/` would be better? There's already a number of console drivers in there.