Makefile: fix target-finalize rule

Fix a bug introduced by the commit a2487758
(Makefile: add support for top-level parallel make).

That commit put a new rule inside the target-finalize rule so it was
erroneously splitted in two parts.

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Cc: Eric Le Bihan <eric.le.bihan.dev@free.fr>
Cc: Thomas De Schampheleire <patrickdepinguin@gmail.com>
Acked-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>