Change in coreboot[master]: soc/mediatek: dsi: fine tune the delta time for EoTp

[Chen-Tsung Hsieh (Code Review)]

Attention is currently required from: Chen-Tsung Hsieh, jitao shi, Shaoming Chen, Jitao Shi, Yu-Ping Wu.
Chen-Tsung Hsieh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51432 )

Change subject: soc/mediatek: dsi: fine tune the delta time for EoTp
......................................................................

Patch Set 5:

(1 comment)

File src/soc/mediatek/common/dsi.c:

https://review.coreboot.org/c/coreboot/+/51432/comment/62c79846_8146baa1 
PS2, Line 207: 10
> Ack

According to https://patchwork.kernel.org/project/linux-mediatek/patch/20210201033603.126...
>     delta = dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST ? 18 : 12;
>   delta += dsi->mode_flags & MIPI_DSI_MODE_EOT_PACKET ? 2 : 0;

If this is what we want, should we update coreboot as follow?
```
    u32 delta = 12;

if (!(mode_flags & MIPI_DSI_MODE_EOT_PACKET))
    	delta += 2;

if (mode_flags & MIPI_DSI_MODE_VIDEO_BURST)
    	delta += 6;
```
(MIPI_DSI_MODE_EOT_PACKET is a disable bit in kernel, but an enable bit in coreboot.)