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

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

BUG=b:270242461
BRANCH=firmware-brya-14505.B
TEST=Verify that the feature is enabled by reading from fsp log

Signed-off-by: Joey Peng <joey.peng@lcfc.corp-partner.google.com>
Change-Id: I82c2016d9dfb39ff7b372815737d4ae62875340c
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73373
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>

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

@@ -44,6 +44,10 @@ fw_config
 	end
 end
 chip soc/intel/alderlake
+	register "domain_vr_config[VR_DOMAIN_IA]" = "{
+		.enable_fast_vmode = 1,
+	}"
+
 	# As per Intel Advisory doc#723158, the change is required to prevent possible
 	# display flickering issue.
 	register "usb2_phy_sus_pg_disable" = "1"