Change in coreboot[master]: mb/google/volteer: Create APIs for USB-C DP alternate mode support

[Derek Huang (Code Review)]

Attention is currently required from: Furquan Shaikh, Tim Wawrzynczak, Curtis Chen, Zhuohao Lee, Brandon Breitenstein.
Derek Huang has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57139 )

Change subject: mb/google/volteer: Create APIs for USB-C DP alternate mode support
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Patch Set 10:

(1 comment)

File src/soc/intel/common/block/tcss/tcss.c:

https://review.coreboot.org/c/coreboot/+/57139/comment/a81106a5_dc764856 
PS9, Line 296: WAIT_FOR_DISPLAYPORT_TIMEOUT
> Yes, we have a draft idea at my 8/26 comment. […]

mainboard_tcss_wait_for_displayport() checks if any device is connected on the specified port first, if nothing is connected it returns immediately, it won't wait for DP device and HPD

So the worse case is 2 * WAIT_FOR_DISPLAYPORT_TIMEOUT = 2 seconds if port-0 and port-1 are connected to non-DP devices, and port-3 is connected to DP