mb/google/brya/var/kinox: Enable SaGv

Enable SaGv support for Kinox

BUG=b:238153479
TEST=Build and boot to Chrome OS

Signed-off-by: Dtrain Hsu <dtrain_hsu@compal.corp-partner.google.com>
Change-Id: Id4646f1621a414a1ec4e272c826b0baea2bb4e19
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65340
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

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

@@ -7,6 +7,8 @@ fw_config
 end
 
 chip soc/intel/alderlake
+	register "sagv" = "SaGv_Enabled"
+
 	# GPE configuration
 	register "pmc_gpe0_dw1" = "GPP_H"