mb/google/rex/var/screebo: Modify TCC_offset to 20

Follow thermal team request, override tcc_offset to 20.

TEST=Build and verified by thermal team using google/screebo.

Change-Id: Idc76f9c0054f21f066b779e6404a1c175eb396a0
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80159
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
diff --git a/src/mainboard/google/rex/variants/screebo/overridetree.cb b/src/mainboard/google/rex/variants/screebo/overridetree.cb
index a3ab01c..c66b5cb 100644
--- a/src/mainboard/google/rex/variants/screebo/overridetree.cb
+++ b/src/mainboard/google/rex/variants/screebo/overridetree.cb
@@ -90,6 +90,9 @@
 		[PchSerialIoIndexI2C5] = PchSerialIoPci,
 	}"
 
+	# Override TCC of 90C = Tj max (110) - TCC_Offset (20)
+	register "tcc_offset" = "20"
+
 	# Acoustic Noise settings and slew rate configuration:
 	#  slew rate for IA Domain: Fast/8
 	#  slew rate for GT Domain: Fast/8