util/bincfg's Makefile already has target that generates flash descriptor. Use it instead. Change-Id: I1756514e1ab7b64de23a98314d8a32e9258e648c Signed-off-by: Evgeny Zinoviev <me@ch1p.io> Reviewed-on: https://review.coreboot.org/c/coreboot/+/39762 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Angel Pons <th3fanbus@gmail.com>