kconfig: jump to linked menu prompt

If clicking on of the links, which leads to a visible prompt, jump to it in
the symbol list.

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>