mb/amd/mandolin: fix AUX/HDP mapping for last DDI port on Dali

We hit a similar issue on Cereme, so I checked the trembyle base board
which also uses AUX4/HDP4 for the last DDI port, so using AUX3/HDP3 is
wrong there.

Change-Id: I99f9426969488cc5c5a14bd432b38bfd69ae7ef0
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44688
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Matt Papageorge <matthewpapa07@gmail.com>
Reviewed-by: Jason Glenesk <jason.glenesk@gmail.com>

src/mainboard/amd/mandolin/variants/mandolin/port_descriptors.c

@@ -193,8 +193,8 @@ static const fsp_ddi_descriptor dali_ddi_descriptors[] = {
 	},
 	{ /* DDI2 - DP */
 		.connector_type = DP,
-		.aux_index = AUX3,
-		.hdp_index = HDP3,
+		.aux_index = AUX4,
+		.hdp_index = HDP4,
 	}
 };