Update vboot submodule to upstream main

Updating from commit id 25b94935:
    vboot_ref/futility: Wrap flashrom_drv behind USE_FLASHROM

to commit id 61971455:
    vboot_ref/Makefile: Expose symbols irregardless of USE_FLASHROM

This brings in 90 new commits.

BUG=b:207808292,b:231152447
TEST=builds with vboot_ref uprev.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Change-Id: Id542f555732b58e1205e757393f9d5fdbde2de68
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64706
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
diff --git a/3rdparty/vboot b/3rdparty/vboot
index 25b9493..6197145 160000
--- a/3rdparty/vboot
+++ b/3rdparty/vboot
@@ -1 +1 @@
-Subproject commit 25b9493525325dfb5bc2c36321c43ec7665060fa
+Subproject commit 61971455ccb99fc6da03c493dfcda102e71aee2f