ARM: mvebu: Add Device Bus and CFI flash memory support to defconfig

This patch selects the devbus driver as part of the mvebu default
config, along with the required options to detect and support
CFI flash memories.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>