mb/google/dedede/var/pirika: Add FW_CONFIG probe for EXT_VR

Add FW_CONFIG probe for absent FIVR bypass mode on peezer.

BUG=b:296982082
BRANCH=firmware-dedede-13606.B
TEST=emerge-dedede coreboot chromeos-bootimage

Change-Id: I0b2053b2d732fd9462686ed7b0c9225539b28fb2
Signed-off-by: Daniel_Peng <Daniel_Peng@pegatron.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77396
Reviewed-by: Karthik Ramasubramanian <kramasub@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/dedede/variants/pirika/Makefile.inc

@@ -3,3 +3,4 @@
 ramstage-y += variant.c
 
 ramstage-y += gpio.c
+ramstage-y += ramstage.c

src/mainboard/google/dedede/variants/pirika/ramstage.c

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#include <baseboard/variants.h>
+#include <fw_config.h>
+#include <soc/soc_chip.h>
+
+static void ext_vr_update(void)
+{
+	struct soc_intel_jasperlake_config *cfg = config_of_soc();
+
+	if (fw_config_probe(FW_CONFIG(EXT_VR, EXT_VR_ABSENT)))
+		cfg->disable_external_bypass_vr = 1;
+}
+
+void variant_devtree_update(void)
+{
+	ext_vr_update();
+}