kbuild: fix oldnoconfig to do the right thing

Commit 861b4ea4

 broke oldnoconfig when removed the oldnoconfig checks on
                       if (input_mode == nonint_oldconfig ||
                           input_mode == oldnoconfig) {
                               if (input_mode == nonint_oldconfig &&
                                   sym->name &&
                                    !sym_is_choice_value(sym)) {
to avoid oldnoconfig chugging through the else stanza.

Fix that to restore expected behaviour (which I've confirmed in the
Fedora kernel build that the configs end up looking the same.)

Signed-off-by: Kyle McMartin <kyle@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>