vboot: save whether developer mode is enabled

Save whether or not vboot has selected developer mode as a flag
in vboot_working_data.  Other coreboot code may access this flag
without needing to consult vboot_handoff (which is in the process
of being deprecated).

BUG=b:124141368, b:124192753
TEST=make clean && make test-abuild
BRANCH=none

Change-Id: Ieb6ac4937c943aea78ddc762595a05387d2b8114
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32843
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/security/vboot/misc.h

@@ -47,6 +47,8 @@ struct vboot_working_data {
  */
 /* vboot requests display initialization from coreboot. */
 #define VBOOT_WD_FLAG_DISPLAY_INIT (1 << 0)
+/* vboot has selected developer mode. */
+#define VBOOT_WD_FLAG_DEVELOPER_MODE (1 << 1)
 
 /*
  * Source: security/vboot/common.c