config: android-base: add CONFIG_IKCONFIG option

This adds CONFIG_IKCONFIG and CONFIG_IKCONFIG_PROC options, which are a
requirement for the O release.

Reviewed-at: https://android-review.googlesource.com/#/c/364553/



Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
[AmitP: cherry-picked this change from Android common kernel]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>