mb/google/brya/var/nereid: Add separate VBT for HDMI

BUG=b:226848617
TEST=HDMI works on nereid

Cq-Depend: chrome-internal:4650256
Signed-off-by: Reka Norman <rekanorman@google.com>
Change-Id: I6a90d3d86b32f73ec0130e582539d1c5b045da62
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63239
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kangheui Won <khwon@chromium.org>

src/mainboard/google/brya/variants/nereid/Makefile.inc

@@ -5,3 +5,4 @@ romstage-y += gpio.c
 romstage-y += memory.c
 
 ramstage-y += gpio.c
+ramstage-y += variant.c

src/mainboard/google/brya/variants/nereid/variant.c

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <drivers/intel/gma/opregion.h>
+#include <fw_config.h>
+
+const char *mainboard_vbt_filename(void)
+{
+	if (fw_config_probe(FW_CONFIG(DB_USB, DB_1A_HDMI)))
+		return "vbt-nereid_hdmi.bin";
+
+	return "vbt.bin";
+}