vboot: copy data structures to CBMEM for downstream use

For platforms that do not employ VBOOT_STARTS_IN_ROMSTAGE,
vboot verification occurs before CBMEM is brought online.
In order to make vboot data structures available downstream,
copy vb2_working_data from CAR/SRAM into CBMEM when CBMEM
comes online.  Create VBOOT_MIGRATE_WORKING_DATA config
option to toggle this functionality.

BUG=b:124141368, b:124192753
TEST=Built and deployed on eve with STARTS_IN_BOOTBLOCK
TEST=Built and deployed on eve with STARTS_IN_ROMSTAGE
TEST=util/lint/checkpatch.pl -g origin/master..HEAD
TEST=util/abuild/abuild -B -e -y -c 50 -p none -x
BRANCH=none

Change-Id: I62c11268a83927bc00ae9bd93b1b31363b38e8cf
Signed-off-by: Joel Kitching <kitching@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31329
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/security/vboot/vboot_logic.c

@@ -438,5 +438,6 @@ void verstage_main(void)
 
 	printk(BIOS_INFO, "Slot %c is selected\n", is_slot_a(&ctx) ? 'A' : 'B');
 	vb2_set_selected_region(region_device_region(&fw_main));
+	vb2_finalize_work_context(&ctx);
 	timestamp_add_now(TS_END_VBOOT);
 }