kconfig: add symbol option config syntax

kconfig: add symbol option config syntax

This adds the general framework to the parser to define options for config
symbols with a syntax like:

config FOO
	option bar[="arg"]

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>