[XL] Change in coreboot[main]: soc/mediatek/common/dp: Move common functions to dptx_hal_common.c

[Yidi Lin (Code Review)]

Attention is currently required from: Hung-Te Lin, Yu-Ping Wu.

Yidi Lin has posted comments on this change by Yidi Lin. ( https://review.coreboot.org/c/coreboot/+/85861?usp=email )

Change subject: soc/mediatek/common/dp: Move common functions to dptx_hal_common.c
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Patch Set 4:

(1 comment)

File src/soc/mediatek/common/dp/dptx_hal_common.c:

https://review.coreboot.org/c/coreboot/+/85861/comment/5d7977e5_be50d977?usp... :
PS3, Line 115: 	DP_CLRSETBITS(mtk_dp, REG_303C_DP_ENCODER0_P0 + 1, val, 0x7);
> This would be wrong for mt8196, where its code is `mtk_dp_mask(mtk_dp, REG_303C_DP_ENCODER0_P0, val  […]

I define `DP_CLRSETBITS` on mt8196 like this.
```
#define DP_CLRSETBITS(mtk_dp, reg, var, mask) \
        mtk_dp_mask(mtk_dp, (reg) - (reg) % 2, \ 
                    (var) << (8 * ((reg) % 2)), (mask) << (8 * ((reg) % 2)))
```

`mtk_dp_mask(mtk_dp, REG_303C_DP_ENCODER0_P0, val << 8, 0x7 << 8)` is converted to `DP_CLRSETBITS(mtk_dp, REG_303C_DP_ENCODER0_P0 + 1, val, 0x7)`.