[S] Change in coreboot[main]: drivers/intel/usb4: Add mainboard function to get EC port

[Derek Huang (Code Review)]

Attention is currently required from: Dinesh Gehlot, Eran Mitrani, Intel coreboot Reviewers, Jakub "Kuba" Czapiga, Kapil Porwal, Subrata Banik, Tarun.

Derek Huang has posted comments on this change by Derek Huang. ( https://review.coreboot.org/c/coreboot/+/86673?usp=email )

Change subject: drivers/intel/usb4: Add mainboard function to get EC port
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Patch Set 4:

(1 comment)

File src/soc/intel/meteorlake/retimer.c:

https://review.coreboot.org/c/coreboot/+/86673/comment/994ae86d_38ee948a?usp... :
PS3, Line 16: 	int ec_port = 0;
            : 
            : 	ec_port = mainboard_retimer_get_index_for_typec(typec_port);
            : 	if (ec_port >= 0) {
            : 		printk(BIOS_INFO, "USB Type-C %d mapped to EC port %d\n", typec_port,
            : 		       ec_port);
            : 		return ec_port;
            : 	} else {
            : 		ec_port = 0;
            : 	}
>

Updated accordingly. In most cases the function returns -1 because the mapping is sequential and no override function is implemented, so I think we don't need the warning print, we can always check `USB Type-C %d mapped to EC port %d` to see if the mapping correct.