[M] Change in coreboot[main]: google/*: Clean up Kconfg board selection for Google MTK boards

[Yidi Lin (Code Review)]

Attention is currently required from: Felix Singer, Hung-Te Lin, Julius Werner, Yu-Ping Wu.

Yidi Lin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79063?usp=email )

Change subject: google/*: Clean up Kconfg board selection for Google MTK boards
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Patch Set 1:

(1 comment)

File src/mainboard/google/corsola/Kconfig:

https://review.coreboot.org/c/coreboot/+/79063/comment/f16551d5_86ea6fae :
PS1, Line 22: 	select DRIVER_ANALOGIX_ANX7625 if BOARD_GOOGLE_CHINCHOU
> > Hmm... […]

I prefer Yu-Ping's idea in the first comment.
```
config CORSOLA_HAS_MIPI_PANEL
    def_bool BOARD_GOOGLE_STARYU_COMMON
config DRIVER_ANALOGIX_ANX7625
    def_bool BOARD_GOOGLE_KINGLER_COMMON || BOARD_GOOGLE_CHINCHOU || ...
    depends on !CORSOLA_HAS_MIPI_PANEL
config DRIVER_PARADE_PS8640
    def_bool !DRIVER_ANALOGIX_ANX7625 || BOARD_GOOGLE_STEELIX
    depends on !CORSOLA_HAS_MIPI_PANEL
```
Make the MIPI/DP bridge driver options mutually exclusive by driver config, but make the expectations by board config.