kconfig: oldconfig shall not set symbols if it does not need to

kconfig: oldconfig shall not set symbols if it does not need to

commit f82f3f9422d4da1eeec6f6cf3e64c6c34c4fe19b in mainline.

Avoid setting the value if the symbol doesn't need to be changed or can't
be changed. Later choices may change the dependencies and thus the
possible input range.

make oldconfig from a 2.6.22 .config with CONFIG_HOTPLUG_CPU not set
was in some configurations setting CONFIG_HOTPLUG_CPU=y without asking,
even when there was no actual requirement for CONFIG_HOTPLUG_CPU.
This was triggered by SUSPEND_SMP that does a select HOTPLUG_CPU.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Tested-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>