Change in coreboot[master]: soc/mediatek/mt8186: Add a stub implementation of the MT8186 SoC

[Rex-BC Chen (Code Review)]

Attention is currently required from: Hung-Te Lin, Paul Menzel, Yu-Ping Wu, Felix Held.
Rex-BC Chen has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/58640 )

Change subject: soc/mediatek/mt8186: Add a stub implementation of the MT8186 SoC
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Patch Set 4:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/58640/comment/6853e634_6a3e9fe4 
PS2, Line 10:
> Rex, could you add a short paragraph explaining the similarities and differences between mt8186 and  […]

Done

File src/soc/mediatek/mt8186/include/soc/timer.h:

https://review.coreboot.org/c/coreboot/+/58640/comment/cb5c7d4d_98071ff2 
PS3, Line 9: TIE_0_EN = 1 << 3,
           : 	COMP_15_EN = 1 << 10,
           : 	COMP_20_EN = 1 << 11,
           : 	COMP_25_EN = 1 << 12,
> Rex, if these constants are always the same for platforms using v2 timer, please move them into time […]

I think I would move these to v2 on upcoming patches.
This is just a init patch.