kconfig: Don't go out from read config loop when you read new symbol

commit 8baefd30 of linux-next replaced
a `switch()' statement with some `if()' statements, but left `break's
in the `switch()' statement untouched. This cause read config loop to
exit and so "make oldconfig" is not much usable (see below).

> $ make oldconfig
><snip>
> scripts/kconfig/conf --oldconfig Kconfig
> #
> # using defaults found in /boot/config-2.6.34-ccs-r1
> #
> *
> * Restart config...
> *
> *
> * General setup
> *
> Prompt for development and/or incomplete code/drivers (EXPERIMENTAL) [N/y/?] (NEW)

(I've already have "CONFIG_EXPERIMENTAL=y" in the old config file. But
that's not read here.)

This patch should fix this problem.

Signed-off-by: Naohiro Aota <naota@elisp.net>
Signed-off-by: Michal Marek <mmarek@suse.cz>