mb/google/brya/var/kuldax: Enable Fast VMode for kuldax

Fast VMode nmakes the SoC throttle when the current exceeds the I_TRIP
threshold.

BUG=b:285406822
BRANCH=firmware-brya-14505.B
TEST=Verify that the feature is enabled by reading from fsp log

Change-Id: I9ae58d704cba8124c6cb9865431aff84c9d154f7
Signed-off-by: David Wu <david_wu@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75600
Reviewed-by: Bob Moragues <moragues@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Derek Huang <derekhuang@google.com>

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

@@ -12,6 +12,10 @@ fw_config
 end
 
 chip soc/intel/alderlake
+	register "domain_vr_config[VR_DOMAIN_IA]" = "{
+		.enable_fast_vmode = 1,
+	}"
+
 	register "sagv" = "SaGv_Enabled"
 
 	register "usb2_ports[1]" = "USB2_PORT_EMPTY"	# Disable USB2 Port 1