Change in coreboot[master]: mb/google/guybrush/var/dewatt: Override SPI fast speed

[Martin L Roth (Code Review)]

Attention is currently required from: Kenneth Chan, Karthik Ramasubramanian.
Martin L Roth has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/63753 )

Change subject: mb/google/guybrush/var/dewatt: Override SPI fast speed
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Patch Set 1:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/63753/comment/d8e93527_9bd17601 
PS1, Line 9: 100 MHz SPI fast speed can be
           : enabled for SPI ROM.
Awesome!

File src/mainboard/google/guybrush/Kconfig:

https://review.coreboot.org/c/coreboot/+/63753/comment/c3b2526b_1402398e 
PS1, Line 140: 	default 0x3 if BOARD_GOOGLE_DEWATT
Nit: Could we get a comment like the lines above saying what the speed for '3' is?
Really it could go on all of these, but if you could do it for dewatt, that'd be a start.