[L] Change in coreboot[main]: soc/mediatek: Add common implementation to configure display

[Yu-Ping Wu (Code Review)]

Attention is currently required from: Hung-Te Lin, Paul Menzel, Yidi Lin.

Yu-Ping Wu has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79776?usp=email )

Change subject: soc/mediatek: Add common implementation to configure display
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Patch Set 3:

(1 comment)

File src/soc/mediatek/mt8188/include/soc/ddp.h:

https://review.coreboot.org/c/coreboot/+/79776/comment/2b23634d_255a4efd :
PS3, Line 286: void mtk_ddp_init(void);
             : void mtk_ddp_mode_set(const struct edid *edid, enum disp_path_sel path);
Since these 2 functions are called from common/display.c, the declarations should also be moved to a common header.