Change in flashrom[master]: Add mediatek_i2c_spi interface

[Neill Corlett (Code Review)]

Attention is currently required from: Nico Huber, Angel Pons.
Neill Corlett has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/61288 )

Change subject: Add mediatek_i2c_spi interface
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Patch Set 3:

(4 comments)

Patchset:

PS1:
> Thank you very much! it helps a lot to know what we are dealing with here. […]

Will address in a follow-up change as needed

File mediatek_i2c_spi.c:

https://review.coreboot.org/c/flashrom/+/61288/comment/337dcca9_c0fcce64 
PS1, Line 242: GPIO line
> At the very least, I'd add an option to enable WP# control.

Will address in a follow-up change as needed

https://review.coreboot.org/c/flashrom/+/61288/comment/ae9bb281_f759f7a9 
PS1, Line 249: 0x426, 7
> Having seen these kinds of datasheets before I know what you mean Neill lol. […]

Ack

https://review.coreboot.org/c/flashrom/+/61288/comment/2896e5f3_ea71de24 
PS1, Line 255: 0x428, 7
> What are these magic numbers?

See line #249