mb/google/volteer/var/voxel: disable DdiPortHpd

GPP_A19 and GPP_A20 set no connection, disables DdiPort1Hpd and DdiPort2Hpd

BUG=b:169690329
TEST=build and verify type-c(C0/C1) port functional normally

Signed-off-by: Pan Sheng-Liang <sheng-liang.pan@quanta.corp-partner.google.com>
Change-Id: I4405526ae777332d3c72041db7b4eda25ae31b8e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46069
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: TH Lin <t.h_lin@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/google/volteer/variants/voxel/overridetree.cb b/src/mainboard/google/volteer/variants/voxel/overridetree.cb
index 8ce6875..d7a265b 100644
--- a/src/mainboard/google/volteer/variants/voxel/overridetree.cb
+++ b/src/mainboard/google/volteer/variants/voxel/overridetree.cb
@@ -1,4 +1,6 @@
 chip soc/intel/tigerlake
+	register "DdiPort1Hpd" = "0"
+	register "DdiPort2Hpd" = "0"
 	register "tcc_offset" = "5"     # TCC of 95
 
 	register "power_limits_config[POWER_LIMITS_U_2_CORE]" = "{