mb/google/rex/var/screebo: Configure slew rate to 1/8 for GT domain

set slew rate to 1/8 for GT domain.

BUG=b:312405633
BRANCH=none
TEST=Able to build and boot google/screebo

Change-Id: Ib5cb07b7effc4a51c2119183010a03e026f639f8
Signed-off-by: Kun Liu <liukun11@huaqin.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79628
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Eric Lai <ericllai@google.com>
Reviewed-by: Rui Zhou <zhourui@huaqin.corp-partner.google.com>
diff --git a/src/mainboard/google/rex/variants/screebo/overridetree.cb b/src/mainboard/google/rex/variants/screebo/overridetree.cb
index 0a66fdb..3af628d 100644
--- a/src/mainboard/google/rex/variants/screebo/overridetree.cb
+++ b/src/mainboard/google/rex/variants/screebo/overridetree.cb
@@ -92,10 +92,13 @@
 
 	# Acoustic Noise settings and slew rate configuration:
 	#  slew rate for IA Domain: Fast/8
+	#  slew rate for GT Domain: Fast/8
 	#  Ignore slew rate configuration for SA Domain
 	register "enable_acoustic_noise_mitigation" = "1"
 	register "disable_fast_pkgc_ramp[VR_DOMAIN_IA]" = "1"
 	register "slow_slew_rate_config[VR_DOMAIN_IA]" = "SLEW_FAST_8"
+	register "disable_fast_pkgc_ramp[VR_DOMAIN_GT]" = "1"
+	register "slow_slew_rate_config[VR_DOMAIN_GT]" = "SLEW_FAST_8"
 	register "slow_slew_rate_config[VR_DOMAIN_SA]" = "SLEW_IGNORE"