Fix compilation if CONFIG_INTERNAL=no

Change-Id: Id9e07332003832465a0eccf1d89e73d15abb35c0
Signed-off-by: Jonathan Liu <net147@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/35808


Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>