mb/google/guybrush: Add STAPM values to overridetree

This enables STAPM power management.  Values follow the AMD
specification.

BUG=b:185209734
TEST=Build & Boot guybrush

Signed-off-by: Martin Roth <martinroth@chromium.org>
Change-Id: Ib9f2ec9a8ac118c55ae53b9419ea4ff74ce7b599
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52650
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: chris wang <Chris.Wang@amd.com>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
diff --git a/src/mainboard/google/guybrush/variants/guybrush/overridetree.cb b/src/mainboard/google/guybrush/variants/guybrush/overridetree.cb
index 0beeea0e..3519170 100644
--- a/src/mainboard/google/guybrush/variants/guybrush/overridetree.cb
+++ b/src/mainboard/google/guybrush/variants/guybrush/overridetree.cb
@@ -35,6 +35,13 @@
 	device domain 0 on
 	end # domain
 
+	register "slow_ppt_limit_mW"         = "25000"
+	register "fast_ppt_limit_mW"         = "30000"
+	register "slow_ppt_time_constant_s"  = "5"
+	register "stapm_time_constant_s"     = "275"
+	register "sustained_power_limit_mW"  = "15000"
+	register "thermctl_limit_degreeC"    = "100"
+
 	# I2C Config
 	#+-------------------+---------------------------+
 	#| Field             |  Value                    |