This patch refactors the main Kconfig file in order to align it with the
Zephyr code style and to make sure that each Kconfig configuration
portion is easily identifiable.
Change-Id: Ib226aaa9a98e9b08a47d9d1c329f18f4f6936620
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@linaro.org>