mb/google/brya0,skolas4es,skolas: disable Tccold Handshake

The patch disables Tccold Handshake to prevent possible display
flicker issue for skolas board. Please refer to Intel doc#723158
for more information.

BUG=b:221461379
BRANCH=firmware-brya-14505.B
TEST=Boot to OS on Skolas, verify upd setting.

Change-Id: Ic184a61c27abd729667cd181d8f9954f58b67856
Signed-off-by: Selma Bensaid <selma.bensaid@intel.com>
Signed-off-by: Bora Guvendik <bora.guvendik@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68636
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/brya/variants/brya0/overridetree.cb

@@ -50,6 +50,10 @@ chip soc/intel/alderlake
 
 	register "sagv" = "SaGv_Enabled"
 
+	# As per Intel Advisory doc#723158, the change is required to prevent possible
+	# display flickering issue.
+	register "disable_dynamic_tccold_handshake" = "true"
+
 	register "platform_pmax" = "145"
 
 	register "usb2_ports[7]" = "USB2_PORT_MID(OC_SKIP)"	# Type-A MLB Port

src/mainboard/google/brya/variants/skolas/overridetree.cb

@@ -50,6 +50,10 @@ chip soc/intel/alderlake
 
 	register "sagv" = "SaGv_Enabled"
 
+	# As per Intel Advisory doc#723158, the change is required to prevent possible
+	# display flickering issue.
+	register "disable_dynamic_tccold_handshake" = "true"
+
 	register "platform_pmax" = "145"
 
 	register "usb2_ports[7]" = "USB2_PORT_MID(OC_SKIP)"	# Type-A MLB Port

src/mainboard/google/brya/variants/skolas4es/overridetree.cb

@@ -46,6 +46,10 @@ chip soc/intel/alderlake
 
 	register "sagv" = "SaGv_Enabled"
 
+	# As per Intel Advisory doc#723158, the change is required to prevent possible
+	# display flickering issue.
+	register "disable_dynamic_tccold_handshake" = "true"
+
 	register "platform_pmax" = "145"
 
 	register "usb2_ports[7]" = "USB2_PORT_MID(OC_SKIP)"	# Type-A MLB Port