Change in coreboot[master]: src/ec/google/chromeec: Add APIs for USB-C DP ALT mode

[Furquan Shaikh (Code Review)]

Attention is currently required from: Tim Wawrzynczak, Derek Huang, Brandon Breitenstein, Curtis Chen.
Furquan Shaikh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57138 )

Change subject: src/ec/google/chromeec: Add APIs for USB-C DP ALT mode
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Patch Set 13: Code-Review+2

(1 comment)

File src/ec/google/chromeec/ec.c:

https://review.coreboot.org/c/coreboot/+/57138/comment/0d999c2f_5b9a6907 
PS13, Line 1675: !(mux_flags & USB_PD_MUX_HPD_LVL) || !(mux_flags & USB_PD_MUX_DP_ENABLED)
nit: This can also be written as :

```
while ((mux_flags & hpd_asserted_mask) != hpd_asserted_mask));
```

where,
```
 hpd_asserted_mask = USB_PD_MUX_HPD_LVL | USB_PD_MUX_DP_ENABLED;
```