Defining defaults for symbols used inside choices is not allowed. Add a
check for this, so we can drop the existent, overly restrictive checks
in the follow-up change.
Change-Id: I45bce2633dbd168fceb81ceae9b68621b28526e8
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57715
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Reviewed-by: Martin Roth <martinroth@google.com>
