[L] Change in coreboot[main]: soc/mediatek/mt8189: Add a stub implementation of MT8189 SoC

[Yidi Lin (Code Review)]

Attention is currently required from: Hung-Te Lin, Vince Liu.

Yidi Lin has posted comments on this change by Vince Liu. ( https://review.coreboot.org/c/coreboot/+/85616?usp=email )

Change subject: soc/mediatek/mt8189: Add a stub implementation of MT8189 SoC
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Patch Set 1:

(1 comment)

Patchset:

PS1: 
```
In file included from src/soc/mediatek/common/cbmem.c:6:
src/soc/mediatek/common/include/soc/emi.h:6:10: fatal error: 'soc/dramc_param.h' file not found
    6 | #include <soc/dramc_param.h>
      |          ^~~~~~~~~~~~~~~~~~~
1 error generated.
make[2]: *** [Makefile:430: /cb-build/coreboot-gerrit.0/clang-chromeos/GOOGLE_SKYWALKER/romstage/soc/mediatek/common/cbmem.o] Error 1
make[2]: Leaving directory '/home/coreboot/node-root/workspace/coreboot-gerrit'
```