Toplevel Make is not aware about changes in the `scripts/config/*conf`
targets and this is causing issues for during update to that part of
build tree, where one needs to handle this manually by either force
rebuilding the targets or running `make config-clean`. Fix this by
forcing the rebuild if necessary.
Fixes: #9297
Signed-off-by: Petr Štetiar <ynezz@true.cz>
