kconfig: fix make oldconfig

Linus wrote:
 This seems to make "make oldconfig" a _lot_ more verbose than it
 used to be. In a very annoying way.

 I just did a quick git bisect. It's introduced by commit 4062f1a4
 ("kconfig: use long options in conf") by Sam Ravnborg. Apparently that
 thing is totally buggy, and doesn't just change the option names, but
 actively breaks them.

The old behaviour (from years ago) were reintroduced by accident.  Fix
this so we are back to the version that are silent if there is nothing
to ask about.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>