mb/google/volteer: set TcssXhciEn to 1

BUG=144874778
TEST=Built with Volteer recipe and verified USB functionality

Change-Id: I6cbdbd8a4f65a0fe19e3fb8d7b60b8b849f104e7
Signed-off-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39357
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/volteer/variants/baseboard/devicetree.cb

@@ -110,6 +110,9 @@ chip soc/intel/tigerlake
 		[PchSerialIoIndexUART2] = PchSerialIoDisabled,
 	}"
 
+	# TCSS USB3
+	register "TcssXhciEn" = "1"
+
 	# DP port
 	register "DdiPortAConfig" = "1"	# eDP
 	register "DdiPortBConfig" = "0"