Change in coreboot[master]: vendor: mediatek: Add mediatek mt8192 dram initialization codes

[Hung-Te Lin (Code Review)]

Attention is currently required from: Xi Chen, Nico Huber, Martin Roth, Paul Menzel, Yu-Ping Wu.
Hung-Te Lin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/50294 )

Change subject: vendor: mediatek: Add mediatek mt8192 dram initialization codes
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Patch Set 11:

(1 comment)

File src/vendorcode/Makefile.inc:

https://review.coreboot.org/c/coreboot/+/50294/comment/541715f2_39aee0fd 
PS8, Line 7: #
> For build pass because coreboot soc dram calibration code already exists, will enable when vendorcod […]

If that's the case, I'd prefer adding a new Kconfig, say MEDIATEK_VENDOR_DRAM_CALIBRATION or MEDIATE_EMI_TIMING_TUNING, and turn on that option later when we remove SOC code.

Or, you can postpone adding the Makefile in mt8192 folder.